According to 1 Kings 11:4 in the Bible, when Solomon was old, his wives "turned his heart after other gods, and his heart was not wholly true to the Lord his God, as was the heart of David his father." The "other gods" to which the verse refers are the idols and deities of the nations from which the women originated, such as Egypt, Moab, Tyre, and Sidon. These idols and deities were worshipped in the temples of Solomon's wives' home countries, and their influence led Solomon to turn away from his faith in the Lord and worship these other gods instead.
In addition to turning Solomon's heart away from the Lord, these wives and their children also brought their own religious and cultural practices to the palace, which had a profound impact on Solomon's rule. The verse goes on to describe how Solomon built temples and dedicated them to many of these foreign gods, and how his worship of these gods led to a breach between him and the Lord.