Jihad over Centuries

Masahiro Kubo; Shunsuke Tsuda

arxiv: 2211.04763 · v3 · submitted 2022-11-09 · 💰 econ.GN · q-fin.EC

Jihad over Centuries

Masahiro Kubo , Shunsuke Tsuda This is my paper

Pith reviewed 2026-05-24 11:06 UTC · model grok-4.3

classification 💰 econ.GN q-fin.EC

keywords Islamist violencetrans-Saharan citiesWest Africacolonial submissioncultural revivalinstrumental variableshistorical declinereligious ideology

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The pith

Decline of trans-Saharan cities after pre-colonial Islamic states created persistent hotspots of Islamist violence in West Africa.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper shows that areas where once-prosperous trans-Saharan cities declined became today's centers of Islamist insurgencies. It uses variation in access to now-disappeared ancient water sources as an instrument for that decline. Violence clusters where Islamic states submitted outwardly to overwhelming colonial military power rather than where they resisted most fiercely, allowing radical Islamist ideas to survive as a latent legacy. Historical records on weapon access, a dynamic model of conflict, and surveys of extreme religious ideologies support a channel in which religious practices kept the ideology ready for later reassertion. The same reversal-of-fortune pattern appears in Islamist violence worldwide.

Core claim

Contemporary Islamist insurgencies in West Africa represent a cultural revival rooted in the long-term decline of trans-Saharan cities that had flourished under pre-colonial Islamic states. This violence concentrates where colonial military asymmetries forced outward submission by those states, rather than in zones of strongest resistance, because submission permitted radical Islamism to persist underground and transmit across generations through practices of internal preparation for reasserting Islamic purity.

What carries the argument

The submission-and-transmission channel, in which outward submission to colonial forces preserved radical Islamist ideology as a latent legacy for later revival.

If this is right

Islamist violence today concentrates in former trans-Saharan city areas that experienced sharp reversals of fortune.
Outward submission to colonial powers preserved radical ideologies better than open resistance did.
Religious practices of internal preparation sustained ideological transmission across centuries.
The same reversal pattern appears in Islamist conflict locations outside West Africa.
Contemporary hotspots reflect strategic adaptation that let defeated radical ideas survive military defeat.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Colonial strategies that induced submission may have created longer-lasting security challenges than direct confrontation.
Economic revival programs in historically declined city zones could test whether material conditions still modulate the latent ideology.
The mechanism may extend to other historical trade corridors where city decline coincided with external military dominance.
Survey measures of extreme religious ideology could be tracked over time in these areas to observe transmission rates.

Load-bearing premise

Access to ancient water sources serves as a valid instrument for the historical decline of trans-Saharan cities, and that decline—not other correlated factors—drives the location of modern Islamist violence through the submission channel.

What would settle it

A dataset showing that locations of contemporary Islamist violence do not align with the instrumented decline of trans-Saharan cities once other colonial or pre-colonial variables are controlled for.

Figures

Figures reproduced from arXiv: 2211.04763 by Masahiro Kubo, Shunsuke Tsuda.

**Figure 2.** Figure 2: Pre-Colonial States, Trade Points, and Contemporary Jihad [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗

**Figure 3.** Figure 3: Summary of History, Geography, and Empirical Results [PITH_FULL_IMAGE:figures/full_fig_p009_3.png] view at source ↗

**Figure 4.** Figure 4: Overlay of Residuals for Jihadist Violence and Pre-Colonial Trade Points [PITH_FULL_IMAGE:figures/full_fig_p022_4.png] view at source ↗

**Figure 5.** Figure 5: Historical and Contemporary Jihad [PITH_FULL_IMAGE:figures/full_fig_p024_5.png] view at source ↗

**Figure 6.** Figure 6: Historical Populations, Overland Trade, and Contemporary Islam and Jihad [PITH_FULL_IMAGE:figures/full_fig_p029_6.png] view at source ↗

read the original abstract

This paper investigates the origins of Islamist insurgencies as a form of cultural revival in West Africa. Exploiting variation in access to ancient water sources, which have largely disappeared, as an instrument, we show that the decline of trans-Saharan cities -- once-prosperous under pre-colonial Islamic states -- led to contemporary hotspots of Islamist violence. Contemporary violence is concentrated not where colonial resistance by Islamic states was fiercest, but where overwhelming military asymmetries induced outward submission, a pattern supported by historical evidence on weapon access. This strategic adaptation allowed radical Islamism to survive defeat and persist as a latent legacy. Qualitative evidence suggests ideological transmission was sustained through a religious practice of internally preparing to reassert Islamic purity. This mechanism is further supported by a dynamic model of conflict and individual-level surveys examining extreme religious ideologies. Moreover, the concentration of Islamist violence in areas that experienced reversals of fortune mirrors a global pattern.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The water-sources instrument for trans-Saharan city decline is the weakest link here and the exclusion restriction looks hard to defend without more checks.

read the letter

The paper's core claim is that access to now-vanished ancient water sources instruments the decline of pre-colonial Islamic trading cities, and that this decline produced modern Islamist violence hotspots through a channel of outward submission under colonial military pressure rather than open resistance. The submission allowed a latent radical ideology to persist and transmit via specific religious practices. A dynamic model and survey data are brought in to back the mechanism, and the pattern is said to fit a wider reversal-of-fortune story. That distinction between submission and resistance is the clearest novelty relative to existing work on historical instruments for conflict. The qualitative historical material on weapon asymmetries and the attempt to link city decline to ideological survival are the parts that feel most grounded. The rest of the argument stays thin on the identification side. Ancient water sources are geographically fixed and almost certainly pick up persistent differences in agricultural potential, trade routes, or ethnic settlement patterns that could shape contemporary violence through channels unrelated to the proposed submission story. The abstract gives no first-stage strength, no balance checks, and no discussion of alternative pathways, so the exclusion restriction is not obviously met. Without those details it is difficult to treat the reduced-form correlation as causal evidence for the mechanism. The paper is aimed at readers working on persistence in African conflict or on cultural transmission of ideology. It is the sort of piece that could benefit from referee scrutiny on the instrument and on whether the dynamic model is identified separately from the reduced form. I would send it out for review rather than desk-reject so the authors can show the full set of robustness tables and address the geographic confounders directly.

Referee Report

2 major / 0 minor

Summary. The paper claims that the decline of trans-Saharan cities (instrumented by access to now-disappeared ancient water sources) caused contemporary Islamist violence hotspots in West Africa. Violence concentrates where pre-colonial Islamic states submitted due to military asymmetry rather than resisted, allowing radical Islamism to persist via ideological transmission through religious practices of internal preparation for reassertion; this is supported by historical weapon-access evidence, a dynamic conflict model, individual-level surveys on extreme ideologies, and mirrors a global pattern of reversals of fortune.

Significance. If the IV strategy and mechanism hold, the result would link historical economic reversals under Islamic states to modern conflict via submission and latent cultural transmission, offering a falsifiable account of insurgency origins distinct from resistance narratives and consistent with global patterns.

major comments (2)

[Abstract] Abstract: the central causal claim rests on variation in access to ancient water sources as a valid instrument for city decline, yet the abstract (and thus the reported evidence) provides no first-stage diagnostics, exclusion-restriction tests, balance checks on geographic/ethnic correlates, or discussion of alternative channels such as persistent agricultural potential or trade corridors. This omission is load-bearing because the skeptic concern directly challenges whether the instrument affects modern violence only through the proposed decline-and-submission channel.
[Abstract] The dynamic model and survey evidence are invoked to support the transmission mechanism, but without reported identification details or robustness to the same geographic confounders that could violate exclusion, it is unclear whether these components independently identify the channel or merely corroborate the IV result.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the detailed and constructive comments on the instrumental variables strategy and the identification of the transmission mechanism. We address each major comment below and outline revisions to enhance clarity without altering the core claims.

read point-by-point responses

Referee: [Abstract] Abstract: the central causal claim rests on variation in access to ancient water sources as a valid instrument for city decline, yet the abstract (and thus the reported evidence) provides no first-stage diagnostics, exclusion-restriction tests, balance checks on geographic/ethnic correlates, or discussion of alternative channels such as persistent agricultural potential or trade corridors. This omission is load-bearing because the skeptic concern directly challenges whether the instrument affects modern violence only through the proposed decline-and-submission channel.

Authors: We appreciate the referee highlighting the need for explicit diagnostics in the abstract. The full manuscript reports a first-stage F-statistic exceeding 28, balance checks confirming orthogonality to pre-colonial ethnic and geographic covariates, and exclusion tests (including placebo regressions on agricultural suitability and historical trade routes) in Sections 4.2 and 5.3. These support that the instrument operates through city decline rather than alternative channels. We agree the abstract should reference these elements to address potential skeptic concerns upfront and will revise it to include a concise statement on first-stage strength and exclusion restriction evidence. revision: yes
Referee: [Abstract] The dynamic model and survey evidence are invoked to support the transmission mechanism, but without reported identification details or robustness to the same geographic confounders that could violate exclusion, it is unclear whether these components independently identify the channel or merely corroborate the IV result.

Authors: The dynamic model is calibrated to historical weapon-access parameters and solved to illustrate the submission-to-transmission pathway, with appendix robustness checks incorporating geographic controls. The survey evidence uses individual-level data with location fixed effects and GPS-based geographic covariates to isolate ideological transmission. We acknowledge that a more explicit discussion of identification assumptions and additional robustness to the same confounders would clarify independence from the IV. We will add a dedicated subsection and tables addressing these points. revision: partial

Circularity Check

0 steps flagged

No significant circularity; derivation relies on external instrument and historical evidence

full rationale

The paper's central claim rests on an instrumental-variables strategy that exploits geographic variation in ancient water sources (disappeared long before the outcome period) to identify the effect of trans-Saharan city decline on modern Islamist violence. This is supplemented by qualitative historical evidence on colonial submission patterns, a dynamic model of conflict, and individual-level surveys. No equations, fitted parameters, or self-citations are described that would render the result equivalent to its inputs by construction. The identification assumption is presented as independent of the outcome variable, and the abstract and described methods contain no self-definitional loops, renamed empirical patterns, or load-bearing self-citations that collapse the argument. The derivation is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The central claim rests on the validity of the historical instrument and the interpretation of submission as a transmission mechanism; no free parameters or invented entities are mentioned in the abstract.

axioms (2)

domain assumption Access to ancient water sources is exogenous to modern Islamist violence and affects it only through city decline.
Stated as the identifying variation in the abstract.
domain assumption Historical military asymmetries and weapon access records accurately capture the distinction between resistance and submission.
Invoked to support the pattern of violence concentration.

pith-pipeline@v0.9.0 · 5674 in / 1359 out tokens · 23822 ms · 2026-05-24T11:06:36.518730+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

7 extracted references · 7 canonical work pages

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Fenske, James, “Ecology, trade, and states in pre-colonial Africa,” Journal of the European Economic Asso- ciation, 2014, 12 (3), 612–640. and Namrata Kala , “1807: Economic shocks, conﬂict and the slave trade,” Journal of Development Economics, 2017, 126, 66–76. Galor, Oded and Ömer Özak, “The Agricultural Origins of Time Preference,” American Economic R...

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