I am searching for a clan with Bulgarians. Do you know in which kingdom there are such
There are many. Go to search on settings and click the language as Bulgarian.
One of the first few that shows up is:
[BuL] BulgarianUnitedLions in #155
[bul] BULGARIAN TROY #155
[BGL Bulgarian League 1 #155
Most Bulgarian guilds are in #155 I presume
Hope that helps