Pul king of Assyria invaded the land, so Menahem gave Pul 75,000 pounds of silver so that Pul would support him to strengthen his grip on the kingdom.
2 Kings 15:19 In-Context
In the thirty-ninth year of Azariah king of Judah, Menahem son of Gadi became king of Israel, and he reigned in Samaria ten years.
He did evil in the eyes of the LORD. During his entire reign he did not turn away from the sins of Jeroboam son of Nebat, which he had caused Israel to commit.
Then Pul king of Assyria invaded the land, and Menahem gave him a thousand talents of silver to gain his support and strengthen his own hold on the kingdom.
Menahem exacted this money from Israel. Every wealthy person had to contribute fifty shekels of silver to be given to the king of Assyria. So the king of Assyria withdrew and stayed in the land no longer.
As for the other events of Menahem’s reign, and all he did, are they not written in the book of the annals of the kings of Israel?