What justifications/reasons were used to take the land ?

Your question is very ambiguous. Assuming that your question is about colonization, I would try my best to answer. Colonization (taking of land) was justified into three categories: God, gold, and glory.

Explanation:

Europeans justified their colonialism that what their doing is "holy work" because they are widening their religious belief (Christianity) to save indigenous people. They used religion to justified their brutal ways of taking the land away from the "indians" and they believed that by their influence, they were giving them a "better" life. Europeans also justifies their colonization by expanding their kingdom and making them more powerful (glory). Lastly, colonization happened because people seek more riches (gold) and spices.