According to these historians, Alexander's initial army consisted of about 35,000 soldiers, largely comprising infantry and cavalry units from Macedonia, Greece, and other regions of his kingdom. This number included approximately 12,000 phalangites, 5,000 light infantry, and around 6,000 cavalry.
As Alexander expanded his conquests across Asia, he incorporated soldiers from conquered territories into his army. Additionally, he established alliances and recruited contingents from various local populations. These reinforcements swelled his army's size significantly.
Various estimates from ancient historians suggest that at the peak of his conquests, Alexander's army may have reached a total strength of around 45,000 to 50,000 troops. These estimates include approximately 30,000-35,000 infantry, including Greek hoplites, phalangites, and allied troops from regions such as Asia Minor, Egypt, and Persia. Additionally, Alexander's army included around 10,000 cavalry, a combination of Macedonian heavy cavalry, Thessalian cavalry, and allied cavalry units from various regions.
It's worth noting that different historians provide slightly varying estimates of the number of troops that formed Alexander's army, so the exact size may have fluctuated during his campaigns. Despite the variations, it's evident that Alexander's army was a formidable and well-organized force that played a crucial role in his successful conquest of vast territories across Asia.