Earth's Neolithic Cultural Horizon

Earth's Neolithic Cultural-Horizon spread from South Asia and Mesopotamia, onward in all directions, by sea and land.  They mixed with hunter-gatherers a little, but these were agriculturalists, growing grain with sophisticated water-works, and networks of round mounded-settlements. Their ancestors had been in southern Eurasia before and during the ice-age.

Neolithic peoples domesticated donkeys. The oldest known evidence of domesticated donkeys is in East Africa, over 7,000 years ago. This was 2,500 years before domesticated horses in the Western Steppe lands of Eurasia.

Western Steppe Herders (WSH) wielded technologies of wheeled carts and horses, to spread out in explosively fast migrations. These were the spreaders of Proto-Indo-European languages.
  Their ancestry was Eastern (Asian) Hunter-Gatherer, Western (European) Hunter-Gatherer, and Ancient North-Eurasian megafauna hunters.

Before the Bronze Age culture reaches the Atlantic Ocean, Neolithic people build structures like Stone Henge, on the western-island fringes of European lands.  Other stone circles are constructed all over Europe from roughly 5000 BCD to -2500 BCE.

Proto Indo-Europeans, with Western Steppe Herder ancestry, bring Vedic traditions to South Asia.