The former king of Cambodia, Norodom Sihanouk, died earlier this month in China, a country that sheltered and helped him at critical points. 

King Sihanouk was not the first foreign royal to whom China has provided support. When the 400-year-old Sassanid Empire in Persia fell to Muslim Arab invaders in AD651, its royals fled eastwards. 

The son of the last Sassanid king, Pirooz, set up a base in present-day Afghanistan and northern Pakistan from which to recapture Persia. In AD654, he sought military help from China, but Emperor Gaozong, of the Tang dynasty, refused him, in part due to the distance involved.

In AD661, Pirooz approached China again, and this time Gaozong sent an emissary to set up the Persian Garrison and appoint Pirooz as commander. The following year, Emperor Gaozong conferred the title “King of Persia” on Pirooz.

The garrison proved no match for the Arabs, however, and Pirooz fled further east, arriving at the Chinese capital of Changan (present-day Xian city, in Shaanxi province) in AD675. Pirooz was appointed a general in the Chinese army and died in AD677 in Changan. In time, the Persian exiles intermarried with the locals and their descendants became totally assimilated.