In 1019,[13] Hassan, as a representative of the Tayy, entered his tribe into an alliance with the Kalb under Sinan ibn Sulayman and the Kilab under Salih ibn Mirdas.[2] Such an alliance between the three principal Arab tribes of the Levant was unprecedented and was meant to prevent outsider dominance of the Syrian desert and steppe.[13] According to the pact's terms, the Jarrahids would rule Palestine, while the Kalb and Kilab (under the Mirdasids) would rule Damascus and Aleppo, respectively.[1] Al-Hakim's reign ended with his mysterious death in 1021 and he was succeeded by Caliph Ali az-Zahir.[1]