The Chariot is a fast, two-wheel cavalry unit pulled by horses. You must research the Wheel before you can build the Chariot. Other cavalry units include the Cavalry, Scout, War Elephant, Heavy Cavalry, and Cataphract.
Researching Leather Armor, Scale Armor, and Chain Mail increase armor. Toolworking, Metalworking, and Metallurgy increases attack strength. Nobility increases hit points.