Seljuk sultan Kaykavus I reigned during the first quarter of the thirteenth century, a period in which the Seljuk Sultinate of Rum was rising in power and prestige in Central Anatolia. Most significantly, Kaykavus I oversaw the conquest of the port cities of Sinop on the Black Sea and Antalya on the Mediterranean, which would be key to the flourishing trade that developed during the following decades between the Seljuks and other Mediterranean principalities. He is known for his patronage of a hospital and clinic (darüşşifa) in Sivas, which also includes his tomb.

Sources:

Faruk Sümer. Türkiye Diyanet Vakfı İslâm Ansiklopedisi, s.v. "Keykâvus I." http://www.islamansiklopedisi.info  

(accessed October 4, 2017).