The Collaborative International Dictionary of English v.0.48:
Sultanate \Sul"tan*ate\, n. [Cf. F. sultanat.] 1. The rule or dominion of a sultan; sultanship. [1913 Webster] 2. The territory ruled by a sultan. Syn: soldanrie. [PJC]WordNet (r) 3.0 (2006):
sultanate n 1: country or territory ruled by a sultan