As states grew in size, speed of movement became crucial because central power could not hold if rebellions could not be suppressed rapidly. The first solution to this was the chariot which became used in the Middle East from around 1800 BC. First pulled by oxen and donkeys, they allowed rapid traversing of the relatively flat lands of the Middle East. The chariots were light enough that they could easily be floated across rivers. Improvements in the ability to train horses soon allowed them to be used to pull chariots, possibly as early as 2100 BC, and their greater speed and power made chariots even more efficient. The major limitation of the use of chariots is terrain; while very mobile on flat, hard, open ground, this is lost on any sort of rough ground, even sparse trees or bushes, small ravines or streams, or marsh, where they are surpassed in maneuverability by common foot soldiers, and later by cavalry.
The power of the chariot as a device both of transportation and of battle became the central weapon of the peoples of the Ancient Near East in the 2nd millennium BC. The typical chariot was worked by two men: one would be a bowman and fire at the enemy forces, while the other would control the vehicle. Over time, chariots carrying up to five warriors were developed. The effectiveness of these vehicles is still somewhat in doubt. In China, their chariots became the central weapon of the Shang dynasty, allowing them to unify a great area.
Although chariots have been compared to modern-day tanks in the role they played on the battlefield, i.e., shock attacks, this is disputed with scholars pointing out that chariots were vulnerable and fragile, required a level terrain while tanks are all-terrain vehicles, and thus not suitable for use in the way modern tanks have been used as a physical shock force. The chief advantage of the chariot was the tactical mobility they provided to bowmen. Because tightly packed infantry were the formation of choice, in order for ancient generals to maintain command and control during the battle as well as for mutual protection, a force of chariots could stand off at long range and rain arrows down on the infantrymen's heads. Because of their speed, any attempts to charge the chariots could be easily evaded. If, on the other hand, an infantry unit spread out to minimize the damage from arrows, they would lose the benefit of mutual protection and the charioteers could easily overrun them.
From a tactical standpoint this put any force facing chariots on the horns of dilemma, making chariots indispensable to armies of the day. Chariots, however, were complicated pieces of hardware that required specialized craftsmen to maintain them. Such services, therefore, made chariots expensive to own. When chariots were owned by individuals within a society, it tended to give rise to a warrior class of specialists and a feudal system (an example of which can be seen in Homer's The Iliad). Where chariots were publicly owned, they helped in the maintenance and establishment of a strong central government, e.g., the New Egyptian Kingdom. Chariot usage peaked in the Battle of Kadesh in 1274 BC, which was probably the largest chariot battle ever fought, involving perhaps 5,000 chariots.