Here's what said about Tibetan society in a book I mentioned in General Zhaoyun's post link he posted (edit: topic is closed?), it's written by a Chinese scholar who was the China's commissioner in Lhasa prior to World War 2.
QUOTE
There are three main groups in Tibet: the nomads, the farmers, and the townsfolk. The life of the nomads is much the same as in the days of the king Songstan Gampo in the seventh century. Clad in bulky, raw sheepskins they roam about the northern plateau of Tibet with their flocks, and many die without seeing what a Tibetan village is like....In comparison with their southern kin, the nomads are better fed, food from their livestock being plentiful...A more settled and less fortunate people are the farmers. Tied down to the land they cultivate, and living in bondage to the nobility and landowners, the farmers are physically shorter and smaller than the nomads and lead a more cramped spiritual life.
He goes on to describe the poor agriculture that is practiced due to poor soil conditions and poor irrigation.
QUOTE
Tsam Pa, or barley (the staple food of Tibet); turnips; far too few potatoes, for which many soils are well suited; some peas as winter fodder for horses; and in lower altitudes wheat, buckwheat, and millet. Raising of beef and dairy cattle is a sideline of the farmer...
QUOTE
Dressing becomes more elaborate with the town people-composed of traders, government employees, and craftsmen-and most elaborate with the women of noble families. The men of the towns wear cotton or silk shirts beneath their gowns and, rich or poor, they wear a tiny piece of turquoise on the lobe of the right ear as a sign of urbanity...Only nobles who have entered government service may curl their hair into the twin knots mentioned before
QUOTE
A days routine for high-class Tibetans may be summarized as follows: Rising between six and eight in the morning, they first do homage to the family gods. After washing the hands, the lord or lady sprinkles clean water around, using a piece of peacock plume or a kind of Indian plan called Tsa-Ku-Sha, and repeats thrice: "Om Ma Hum" to purify the place. Then squatting, he or she starts readin scriptures, keeping at it for hours at a stretch and drinking innumerable cups of tea before attending to business.
QUOTE
Tibetans as a rule do not care much for vegetables, whbich some think are good only for animals. Meat suits their palates, but their religion forbids killing. However as the Tibetan soil is poor and the climate rigorous, a strictly vegetarian diet is impracticable. So the Tibetans reason that for every Buddhist rule there must be exceptions to suit special conditions. But they kill only sparingly, generally such large animals as cattle or sheep. By sacrificing a few lives, they say, they save many lives. But to kill many small fishes to make a fine dish would be a sin.
There is a lot more described but I just posted a few random bits. Ask me for any specifics and I'll post a few excerpts up (ex: marriage practices, etiquette, birth and death rituals, life in the monasteries, etc...). I have a few other books to draw from as well.