Central Asia — the five "Stans" plus Mongolia/Xinjiang — has been a conquest corridor for 2,500 years. Five structural reasons:
Bounded by Siberia (north), Caspian (west), Himalayas (south), China (east). The Silk Road's northern and southern routes converge here. Whoever controls Central Asia links — or blocks — East-West trade, migration, and military movement.
No enduring indigenous empire unified the steppe after the Mongols. Fragmented khanates, emirates, tribal confederations invited external projection — Persian, Russian, Chinese, British.
Turkic (Kazakh, Kyrgyz, Uzbek, Turkmen), Persianate (Tajik), Mongolic, plus Russian, Ukrainian, Korean, German minorities. Sunni Islam dominant but with Sufi, Shia, secular strands. Divides exploitable by outsiders.
No shared identity transcending clan/tribe/valley until modern nationalism (20th C). Even now, water disputes (Rogun Dam), border tensions (Fergana Valley), and great-power rivalry (Russia, China, US, Turkey, Iran) prevent cohesive defense.
The pattern persists: geography + resources + fragmentation = perennial target.