I know that the Golden Horde eventually became more predominately Turk as time went on, but what was the army made up of when it invaded Hungary and Poland?
The Golden Horde is sometimes also called the 'Kipchak' Horde, and the Mongols got this name from their subordinate: 'Kipchak' were originally byname of the Polovstsians, the neighboring (mainly) nomad groups of the Rus' and settled in the steppes in SE Russia. This group (in fact an aggregates of smaller nomad groups) had had a long history with the Rus', latest since the later half of the 10th century. It is true that the Polovstsians sometimes raided in the lands of Rus' and that the Rus' also did counter-expedition in the steppes, but there were also trading, and even inter-marriage between their elites happened before the Great Tatar Invasion (1237-1242): Such complex relationships between the settled Rus' and the nomad Polovstsians are the best represented in the famous Slavic epic poem, The Tale of Igor's Campaign. In this epic, the prtagonist of this poem, Prince Igor Svyatoslavich of Novgorod - Seversk (d. 1202), took captive by the Polovstsians, together with his son, after their failed expedition to the Don River, but his son later (after the events of epics) married with the daughter of the khan of the Polovstsians. Even the Rus' and the Polovssians made alliance against the first invasion of the new commers from the East, the Mongols, but their allied forces were defeated by the Mongol army by River Kalka in 1223.
While the Mongols did not suffer much from this allied force in 1223, they also met resistances from another power of the nomad group, the Volga–Bulghars. So, they repeatedly delegated small-scale army from the end of 1220s to quash such nomad groups in the E- or SE Russia like the Polovetsians and the Volga-Bulghars. Some scholars even argue that even the initial purpose of the Great Invasion can be primarily not the invasion to the settled area of Russia and Central-Eastern Europe, but the complete subjugation of the nomads.
It is important to note here that the Mongol did not only subjugate these former neighbors of the Rus' before or the first phase of the Great Invasion (Julian the Dominican of Hungary records the names of the subjugated nomad groups east to Russia in the 1230s (Fennell 1983: 93, note 77)), but possibly also recruited / reorganzed some remnants of them into their army in course of their invasion across Russia. A Japanese scholar estimates that about such 'new commers' amounted to ca. half of the Mongol Army (ca. 12,000 - 15,000 [edited] in total, so ca. 6,000 to 8,000 for 'the new commers') in the later phase of the Great Invasion in Eastern Europe (Sugiyama 2007: 158), but I'm not entirely sure whether this estimation is accepted among the Anglo-phone historiography of this period (since he is famous......or rather notorious to rely too much on the Persian primary sources).
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