Explanation:

Nomadic herding or pastoral nomadism is a primitive subsistence activity, in which the herders rely on animals for food, clothing, shelter, tools and transport.

They move from one place to another along with their livestock, depending on the amount and quality of pastures and water, thus there is an irregular pattern of movement.

When we come to the statement given in the question, it says: Climate is extreme, rainfall is scanty and the people used to be nomadic herder.

The question says “used to” and “not use to”, it is in fact describing the Nomadic empires such as Mongols and the question checks your history via geography. Hence the correct answer is 2.

Siberian Tundra must be opted out even if you take it as “use to be” because, in Tundra, the main economic activity is not Nomadic herding but is Hunting. Hunting and trapping reindeer have provided food and hides to the local population.