Shepherding is one of the oldest occupations, beginning some 6,000 years ago in Asia Minor. Sheep were kept for their milk, meat, and especially their wool.
In ancient times shepherds also commonly milked their sheep, and made cheese from this milk; only some shepherds still do this today.
In many societies shepherds were an important part of the economy.
In modern times shepherding has changed dramatically.
In the USA, many sheep herds are flocked over public Bureau of Land Management lands.
Wages are higher than was the case in the past. Keeping a shepherd in constant attendance can be costly. Also, the eradication of sheep predators in parts of the world has lessened the need for shepherds. In places like Britain, hardy breeds of sheep are frequently left alone without a shepherd for long periods of time. More productive breeds of sheep can be left in fields and moved periodically to fresh pasture when necessary. Hardier breeds of sheep can be left on hillsides. The sheep farmer will attend to the sheep when necessary at times like lambing or shearing.
Excerpts from Wikipedia