Short answers, pulled from the story.
Nomadic pastoralism is a form of herding in which livestock are moved in search of fresh pastures, following an irregular pattern of movement. Transhumance, by contrast, involves movement between fixed seasonal pastures. The distinction is often blurred in practice, and in historical cases the regularity of ancient movements is frequently unknown.
There are an estimated 30-40 million nomadic pastoralists worldwide. Most are found in central Asia and the Sahel region of North and West Africa, including groups such as the Fulani, the Tuaregs, and the Toubou, with others in the Middle East, East Africa, and parts of Asia.
Juris Zarins proposed that pastoral nomadism emerged as a distinct cultural lifestyle following a climatic crisis around 6200 BC, when Harifian hunter-gatherers in the Sinai fused with Pre-Pottery Neolithic B agriculturalists to form the Munhata culture. Henri Fleisch separately suggested that the Shepherd Neolithic industry of Lebanon's Beqaa Valley may date to the Epipaleolithic, possibly representing one of the earliest nomadic shepherding cultures.
Nomadic pastoralists herd cattle, water buffalo, yaks, llamas, sheep, goats, reindeer, horses, donkeys, and camels, often keeping mixed species. The specific animals vary by region: reindeer herding is central to Sami culture in northern Europe, while camel, cattle, sheep, and goat herding is especially common among Somalis in Northeast Africa.
Increased enclosure and fencing of land has reduced available grazing area, and nomadic pastoralists form a declining minority in most countries where they are found. Overgrazing, climate change, mining, and agricultural reclamation all place pressure on the grasslands that nomadic herding depends on.
Informal cross-border trade by pastoralists in East Africa is substantial: over 95% of cross-border trade in the region moves through unofficial channels. The informal trade of live cattle, camels, sheep, and goats from Ethiopia to Somalia, Kenya, and Djibouti generates an estimated US$250-300 million annually, roughly 100 times the official trade figure.