Is a version of Iqta used at all? I can't really think of any cultures that it would fit. Of course, other than the temples can be held and inherited thing, I'm not really sure what exactly differentiates Iqta from Feudal. I thought that a lot of the differences were really due to religion.
Iqta could possibly be applied to extremely exotic cultures beyond the Bone Mountains. Asshai and Yi Ti are possible candidates. It'd be nice to give the area some more personality, especially because there isn't much canon information.
Iqta took on some of the mechanics previously given to Islam. You get to hold temples and have decadence, I think. I'll have to look into exactly what differentiates the two.