Central Asia has long been a geostrategic location because of its proximity to the interests of several great powers and regional powers. Strategic geography Central Asia has had both the advantage and disadvantage of a central location between four historical seats of power. From its central location, it has access to trade routes, or lines of attack, to all the regional powers. On the other hand, it has been continuously vulnerable to attack from all sides throughout its history, resulting in political fragmentation or outright power vacuum, as it is successively dominated. To the north, the steppe allowed for rapid mobility, first for nomadic horseback warriors like the Huns and Mongols, and later for Russian traders, eventually supported by railroads. As the Russian Empire expanded to the east, it would also push down into Central Asia towards the sea, in a search for warm water ports. The USSR would reinforce dominance from the north, and attempt to project power as far south as Afghanistan. To the east, the demographic and cultural weight of Chinese empires continually pushed outward into Central Asia. The Han, Tang, and Ming dynasties would conquer parts of Fergana Valley and Tarim Basin, and the later Qing dynasty of China consolidated Chinese control over this area. China would project power into Central Asia, most notably in the case of Afghanistan, to counter Russian dominance of the region. To the southeast, the demographic and cultural influence of South Asia is felt in Central Asia, notably in Tibet, the Hindu Kush, and slightly beyond. Several historical dynasties and powers of South Asia, especially those seated along the Indus River, would expand towards Central Asia. The post-Soviet era was characterized by India and Pakistan in South Asia expanding their interests in the region. India's ability to project power into Central Asia has been limited due to being geographically separated by Pakistan from Central Asia, and the cultural differences between secular India, and what would become a mostly Muslim Central Asia. To the southwest, Middle Eastern powers have expanded into the southern areas of Central Asia. Several Persian empires would conquer and reconquer parts of Central Asia; Alexander the Great's Hellenistic empire would extend into Central Asia; two Arab Islamic empires would exert substantial influence throughout the region; and the modern state of Iran has projected influence throughout the region as well. Turkey, through a common Turkic ethnic identity, has gradually