In the winter of 327 BC, Alexander invited all the chieftains in the remaining five Achaemenid satraps to submit to his authority. Ambhi, then ruler of Taxila in the former Hindush satrapy complied, but the remaining tribes and clans in the former satraps of Gandhara, Arachosia, Sattagydia and Gedrosia rejected Alexander's offer. By spring of 326 BC, Alexander began on his Indus expedition from Bactria, leaving behind 3500 horses and 10,000 soldiers. He divided his army into two groups. The larger force would enter the Indus Valley through the Khyber pass, just as Darius had done 200 years earlier, while a smaller force under the personal command of Alexander entered through a northern route, possibly through Broghol or Dorah Pass near Chitral. Alexander was commanding a group of shield-bearing guards, foot-companions, archers, Agrianians, and horse-javelin-men and led them against the tribes of the former Gandhara satrapy.