There are five highways into Tibet, roughly corresponding to the cardinal directions:
North: The road from Golmud is the easiest legal land route at present. The landscape is beautiful but difficult to appreciate after the long rough ride.
East: There are two highways to Tibet from this side. One starts from Yunnan, and another one from Sichuan. The sceneries you can see along the way are the most beautiful.
West: From Xinjiang to Tibet. It is the hardest one. There are many interesting things for the tourist to see on the way and it is worth considering traveling this way instead of via Mount Kailash.
South: You can get into Tibet through the Friendship Highway linking Nepal and Tibet.
By overland you can enjoy the natural beauties and astonishing landscapes along the way. But it requires a good and strong physical condition. If you are not sure with your health, please consider this way over and over.