A city must have horses in its Strategic Resource box to build a war chariot.
The chariot was the earliest means of transportation in combat other than man's own powers of locomotion. The earliest known chariots, shown in Sumerian depictions from about 2500 BC, were not true chariots but four-wheeled carts with solid wooden wheels, heavy and cumbersome and lacking a pivoting front axle. The Hyksos apparently introduced the Assyrian chariot into Egypt shortly thereafter, where it was perfected for transportation and warfare. Within 500 years, Egyptian, Hittite and Palestinian chariots were extraordinarily light and maneuverable vehicles, the wheels and tires in particular exhibiting great sophistication in design and fabrication. Egyptian war chariots were drawn by either two or three horses, which were harnessed by means of chest girths secured by a pole and a yoke. The decline of the war chariot by the end of the 2nd millennium BC was probably related to the spread of iron weaponry, but it was surely related also to the breeding of horses with sufficient strength and stamina to carry an armed man into battle. Armed horsemen replaced the chariot in most Mediterranean civilizations. The use of chariots in war lingered in areas of slower technological advance, but in classical Egypt they were retained mainly for ceremonial functions.