In 334 BC he invaded the Achaemenid Empire (Persian Empire) and began a series of campaigns that lasted 10 years. Following his conquest of Asia Minor (modern-day Turkey), Alexander broke the power of Persia in a series of decisive battles, including those at Issus and Gaugamela. He subsequently overthrew King Darius III and conquered the Achaemenid Empire in its entirety. At that point, his empire stretched from the Adriatic Sea to the Indus River. Alexander endeavored to reach the "ends of the world and the Great Outer Sea" and invaded India in 326 BC, achieving an important victory over King Porus at the Battle of the Hydaspes. He eventually turned back at the Beas River due to the demand of his homesick troops, dying in Babylon in 323 BC; the city he planned to establish as his capital. He did not manage to execute a series of planned campaigns that would have begun with an invasion of Arabia. In the years following his death, a series of civil wars tore his empire apart.