This is an alternate history that begins in 332 bc, when Alexander the Great conquered Egypt. He was joined by a common peasant who appeared to be a master tactician...
The last real fight, at Babylon, was utterly crushed. There was no resistance to the rest of Persia. The peasant, who called himself Ramesik, had advised Alexander on some winning tactics.
Resistance is almost nonexistent. The Western Indian city-states have all fallen to the great army and the advisor Ramesik. War is beginning to emerge between the states in Northern India, and all Skirmishes are won by Alexander and Ramesik.
Most of Tibet has fallen, so the various city-states have signed a peace treaty. Alexander turns south, looking for the profitable Indian Ocean trade. Meanwhile, in Scandinavia, the Nords conquer all of Scandinavia. Settlements in Russia of the Nords prosper.
The Indian city-states foolishly declared war on Macedonia. Alexander finished mopping up the remainder of India and turned his eyes to Southeast Asia. Some of the soldiers speak of mutiny, but most are strangely compelled to follow him. In Scandinavia, the Nords build great ships.
Diaspora from India migrates up to Siberia/Mongolia. The mongol tribes adopt Indian culture. The Finnish and the Swedish peoples rebel against the Nordic empire, even capturing Norway. As well, the government-in-exile flees to Iceland. The Malay tribes of Southeast Asia are vassalised by Alexander, seeing what they did to India. Alexander then turns his eyes to Japan.
Rest will come tomorrow...