A Feast of Blood Bread

The following is about the Arab conquest of northern Iran in the early eighth century. It relates the story of the proud, recalcitrant Turkish Chol dynasty who consistently reneged on their treaty obligations with the Arabs. So the Arabs had to forcefully subjugate them:

The region was left alone until the reign of Sulayman (715-17), who dispatched the redoubtable general Yazid ibn al-Muhallab to seek its submission. He besieged the incumbent monarch for several months, but was not able to obtain his surrender and agreed to leave on condition of payment of tribute. As soon as he had gone, the locals threw off their allegiance and killed the agent of the government who had been left behind. This provoked a furious reaction from Yazid, who fought them for months until they finally surrendered, and this time "he gibbeted their warriors" and, in fulfillment of an earlier threat, he made bread from their blood and ate it. Thus this country became part of the Arab Empire.

Hoyland, Robert G. In God's Path: The Arab Conquests and the Creation of an Islamic Empire. Oxford University Press, 2015, 118.