The Seljuk Sultanate of Rum was one of the many successor states to the long disestablished Seljuk Empire. In its history, it was able to force the Byzantines (briefly) from Anatolia, and harry the Crusader Kingdoms in Outremer.
But for all the opponents they have faced, they were overcome by one great opponent. The Mongol Empire. The Seljuks suffered a terrible defeat at Kose Dag, from which they never recovered (although their decline could've started before this, it was this battle that actually showed it)
What could the Seljuks have done differently that could've given them a victory at Kose Dag (or an alternative)?