After the 1238 Mongolian invasion of Alania (ancestors of modern Ossetians) in Northern Caucasus, some 30,000 Iranian Alans—renowned warriors—were incorporated into the Mongolian army as elite troops for the Great Khan.  

These Iranian Alanic knights were also part of the Mongolian faction known as the Tartars or the Golden Horde (the faction that controlled medieval Russia).  For these services, Alans may have been rewarded with hereditary grants of land in Moldavia (modern day Iasi in Romania derives its name from Alans).  

Alans fought as a single trained group under their own leadership.  Such Alanic fighting units even served the Byzantine Empire (the Eastern Roman Empire).  Alans were Christians and resented serving Islamized Mongolians or unbelievers.   

During the Comnenian era Byzantine (11^th-12^th c.), frequent marriage alliances took place between Byzantine noblemen and Alanic princesses.  When the newly-established Turks in Anatolia began to cause problems for Byzantine Empire, the Alans at the borders of Bulgaria offered their help.  The Byzantine Empire sent supplies to ensure that Alans had a safe passage so they could enter their military services.

~ source “Journal of Medieval Military History” (2013) by Clifford Rogers et al.

[pic Wikipedia: Here is map of Iranian Alanic territory in ancient Spain http://geocurrents.info/wp-content/uploads/2012/01/Alan_Kingdom_Iberian_Peninsula_Map.jpg...and as we follow the current affairs in Spain, let's recall that Catalonia is "Goth-Alania"… for educational purposes only]