A Toluid-backed kurultai formally proclaimed Möngke as Great Khan, marking the decisive consolidation of Tolui’s line after the Ögedeid regency and setting the stage for a more centralized push to govern the empire’s far-flung territories.
In the aftermath of Möngke’s enthronement, leading opponents from the previous ruling faction were tried and removed from power, helping secure Toluid control over the imperial center and reducing the immediate risk of a counter-coup.
Möngke ordered a multi-year census across much of the empire to standardize assessment of households, manpower, and productive land. The census became a core administrative tool for rationalizing taxation and obligations across diverse regions.
The census program advanced region by region (with North China completed early), illustrating Möngke’s attempt to translate conquest into predictable extraction and administrative legibility across the empire’s major population centers.
To tighten fiscal control and improve revenue administration, Möngke’s government centralized oversight of monetary matters (including paper-money issues in Yuan-ruled China later), reflecting his broader program of auditing and standardization.
Möngke tasked his brother Hülegü with a major western expedition to secure and extend Mongol power in Iran and adjacent lands. This delegation of authority to close kin paired imperial oversight with regional campaigns.
Hülegü’s forces pressed the campaign against Nizari Ismaili strongholds as part of Möngke’s western strategy, using large-scale siege operations and engineering resources to dismantle fortified resistance in northern Iran.
The fall of Maymun-Diz—closely tied to the surrender of Nizari leadership—signaled the collapse of coordinated Nizari resistance and accelerated the Mongol dismantling of their fortress network.
Leaving day-to-day administration at Karakorum to Ariq Böke, Möngke took the field in person against the Southern Song. The move underscored the campaign’s importance and tied imperial legitimacy to continued conquest in China.
During operations in Sichuan, Möngke’s forces captured Paoning (modern Langzhong). The advance strengthened Mongol positions for deeper incursions and pressured Song defenses in the upper Yangtze region.
Hülegü’s forces compelled Baghdad’s surrender, ending Abbasid political power there and dramatically shifting the balance of power in the Islamic world. The conquest also entrenched the Mongol presence in Mesopotamia under the emerging Ilkhanate.
The far northwestern extension of Möngke’s census program reached Novgorod only late in the process, reflecting both the logistical challenges of imperial administration and local resistance to registration and taxation.
Möngke’s 1259 offensive culminated in the protracted siege of the Song fortress of Diaoyu (Diaoyucheng). The fortress held out, becoming a focal point of the campaign and a critical check on Mongol momentum in southern China.
Möngke died while the army was operating around the Diaoyu/Diaoyucheng siege area in Sichuan (modern Chongqing region). His death forced operational withdrawal and triggered a contested succession that soon fractured central authority.
Möngke Khan and the Great Council Period (1251–1259)
