In 195 H (811 CE), Ray stood at the frontier of the territories of Harun's sons, Caliph Muhammad ibn Harun al-Amin and governor Abu Jafar al-Ma'mun ibn Harun. Their advisors had goaded them into war, and when al-Amin's forces, led by former Ray governor 'Ali ibn 'Isa ibn Mahan, marched over the Zagros Mountains from Baghdad, a much smaller, but mobile and well-led defence force, under Tahir ibn al-Husayn, awaited them at Ray. Tahir decided to risk meeting the invaders out on the plain, where his cavalry could be most effective, so the Battle of Ray, brilliantly successful prelude to his counter-invasion of Iraq, actually took place about a day's march from the city.al-Tabari (trans. Michael Fishbein) History, vol. 31: The War Between Brothers, New York, SUNY Press (1992) , p. 51ff When al-Mam'un was thus established as Caliph, Tahir was rewarded with his old governorship of the eastern territories, which continued in the family for decades as a hereditary post.
