Camels replaced wheels for transportation in many parts of the ancient world for three key reasons: 1) Camels are well-adapted to hot desert environments, requiring little water and able to travel long distances. 2) Camels were more efficient than ox carts, able to carry more cargo faster with fewer handlers over rugged terrain without roads. 3) Maintaining roads for wheeled transport was difficult given the terrain, but camels did not need roads to traverse landscapes like deserts and savannahs.