The problem is- sheep and goats are quite damaging to the environment. They graze down plants to the root and will eat almost any vegetation without hesitation. They soon destroy all natural green cover and the soil has a harder time retaining moisture each progressive year. Before long, the land is too dry to support regular agriculture even though the soil is fertile enough and the rainfall should be sufficient. The land erodes, and people find it harder and harder to support themselves because they have turned their own land into desert. That is the story of much of the middle east.
The Israelis- and those others who joined them, made the land bloom again by restoring order. People became secure in the land and didn't need to depend on sheep and goats exclusively. They put forth great effort to restore the cover that had been destoyed by overgrazing. (And it worked.)
There is a huge plot of land in Lybia, I believe, which had been desert as long as anyone could remember, part of that vast and fearsome North African desert. It was BARE, with a bit of scrub and ittle if any grass. About twenty years ago a sheik bought it and fenced it in. He didn't seed it or irrigate it or anything. He just prevented people's wandering herds of goats and sheep from having access. The aerial view of that region is remarkable: it is all still barren desert with a bit if scrub here and there, EXCEPT for this huge hexagonal fenced-off area which is a vibrant green year-round now from all the plants that have grown up. Perhaps if there were a better system of property rights, others could join that sheik and make the whole region green again, as it was long ago.