Magnates often received gifts from monarchs, which significantly increased their wealth. Often, those gifts were only temporary leases, which the magnates never returned (in the 16th century, the anti-magnate opposition among szlachta was known as the ruch egzekucji praw—movement for execution of the laws—which demanded that all such possessions are returned to their proper owner, the king).
What terms were these gifts given?
temporary leases