I always maintained that nomadic civilizations need to operate differently than regular Civ4 "Wonder building" civilizations.
Nomadic empires, sometimes also called steppe empires, Central or Inner Asian empires, are the empires erected by the bow-wielding, horse-riding, nomadic peoples in the Eurasian steppe, from classical antiquity (Scythia) to the early modern era (Dzungars).
Nomadic empires typically operated by establishing a capital city inside a conquered sedentary state, and then by exploiting the existing bureaucrats and commercial resources of that non-nomadic society. As the pattern is repeated, the originally nomadic dynasty becomes culturally assimilated to the culture of the occupied nation before its ultimate overthrow.
Civ 4 engine is not designed to represent nomadic empires, they are represented by barbarians. If one see black city in Central Asia -- it does not mean void, it represents nomadic dynasty as described above.
If you go through
this list -- it will become clear that most Central Asian civs lasted 70-80 turns in DoC timeline.
Timurids had more connection to Mughals than to Gokturks.
Timeline of Turkic people customary starts with Gokturks and ends with end of Seljuks and rise of Osmans. No Timurids. Heirs of Timurids -- Khanates of Khiva and Bukhara are essentially sedentary Uzbek in nature (mix between Indo-European(Iranian) and Turkic). Meaning one either need to represent Central Asia with some pre-Timurid nomadic power (generalized Seljuks, 550-1350AD) or some Timurid++ sedentary civilization (1370-1920) which eventually became part of Russia.
Creating 3rd Turkish civilization is overkill. One can rename Seljuks to Gokturks or Turkic people and make them appear earlier than DoC Seljuks in order for them to do the same thing to Persia and China in 600-700s as Seljuks did to Middle East in 1000s. There have been
3 Perso-Turkic wars before Seljuks and long history of Turkic-Chinese conflicts. They culminated with An Lushan Rebellion which firmly established itself in the top ten deadliest conflicts in the history of this planet. Any playable civilization (Uzbek/Timurid++) should start much later, between Mongol and Mughal spawn, center around Samarkand and be Muslim. UHVs should include Timurid goal (raze the middle east), Shaybanid goal (frustrate Russia and Persia, Khanate of Sibir was ruled by the Shaybanids) and Khiva/Bukhara cultural goal (1511–1920).