The Khitans were known to Muslim Central Asia: in 1026, the Ghaznavid court (in Ghazna, in today's Afghanistan) was visited by envoys from the Liao ruler, he was described as a "Qatā Khan", i.e. the ruler of "Qatā"; "Qatā" or "Qitā" appears in writings of al-Biruni and Abu Said Gardezi in the following decades. The Persian scholar and administrator Nizam al-Mulk (1018–1092) mentions "Khita" and "China" in his "Book on the Administration of the State", apparently as two separate countries (presumably, referring to the Liao and Song Empires, respectively).