Hulagu Khan

Hülegü crosses the Oxus at the opening of his Iranian campaign

The commonly repeated army totals conceal a basic problem: historians have no reliable headcount for the force that crossed the Oxus.

New Year, not spring

Hülegü's main host crossed the Oxus, or Amu Darya, at the end of 1255 or about 1 January 1256 — not in spring.

The crossing brought the expedition from Transoxiana into the approaches to Khurasan. The army then wintered near Shaburghan before entering Quhistan in spring.

Specialists differ only over whether the crossing belongs to the very end of 1255 or to 1–2 January 1256; neither chronology supports “spring.”

What crossed with him

Before crossing, Hülegü summoned previously submitted regional rulers to reaffirm loyalty and supply troops or resources for operations against opponents including the Nizari Ismailis.

The force incorporated siege specialists and equipment brought from China, including 1,000 households of catapult operators and “naphtha shooters.”

Ahead of the host, authorities cleared roads, reserved grazing land and prepared river crossings.

No headcount survives

The specialist survey says no precise total for Hülegü's army survives. One published reconstruction gives 70,000 people leaving Mongolia, but that is not a consensus figure for the force at the Oxus.

Juvayni and Rashid al-Din report an imperial levy of “two out of every ten men,” which historians read as indicating a large, multi-tribal force rather than a reliable count. Reported totals vary widely because sources count different stages, contingents, auxiliaries, families and support personnel.

The western expedition also did not begin here: Hülegü departed Mongolia in 1253, and Kitbuqa's advance guard was already campaigning west of the river.

Sources

Researched 23 Aug 2026 6 sources not yet audited Date disputed

How this was checked

Researched from the web into a fact sheet and rewritten from that sheet. This article has not yet had an independent model audit. How the pipeline works →

Date disputed. Sources disagree; the research places it at ~1256-01.

What the sources leave uncertain

Specialists differ slightly over whether the crossing belongs to the very end of 1255 or 1–2 January 1256. Neither chronology supports 'spring.'
Reported army totals vary widely because sources count different stages, contingents, auxiliaries, families and support personnel. The listed 80,000 and article's 138,000 should not be treated as verified headcounts.
The surviving sources do not describe Hülegü's commission identically. The Nizari strongholds were clearly an early objective; Baghdad became the target of a separate final advance at the end of 1257.