The news of the returning Babylonian exiles and the initial construction of the Second Temple creates ripples throughout the land, quickly catching the attention of hostile local populations. These enemies are not native to the region. The primary approach among commentators is that they are foreign, idol-worshipping nations brought in by the Assyrian king, Sennacherib. He relocated them from areas like Babylon and Cuthah to settle in the cities of Samaria after the Israelites were exiled. Due to their geographical origins, they are sometimes referred to as Cuthim [רלב״ג].
Providing a deeper historical and religious background, [רב סעדיה גאון] explains that these groups are known as "lion converts." When they first arrived in the land, they did not fear God. Consequently, lions were sent among them, causing deadly attacks. Driven purely by a fear of these animals, they underwent a conversion process, but they did not become genuinely righteous. Instead, they formed a mixed religious practice, showing a fear of God while simultaneously continuing to worship their old idols.
These settlers lived continuously in the land of Israel since the era of the First Temple. They remained there throughout the years of destruction and the successive exiles under Babylon, Media, and Persia, staying right up until Ezra and his followers arrived to rebuild the sanctuary.