The “empire” of Israel refers to the twelve tribes, which came from the twelve children of Jacob, Abraham’s grandson. Abraham changed his name from Abram per his god’s instructions, his grandson Jacob changed his name to Israel for the same reason. Their claim to the land stems from a promise they believe their god made to their forefather Abraham. Over the millenia they have been involved with many empires, conquering some, being conquered by others. Some of these conquering empires, the Assyrians and the Babylonians in particular, intentionally scattered the tribe members across their empires in order to keep them from revolting. These exilic events were the beginning of the greater Jewish diaspora that has existed in some form or another for the thousands of years since. So the empires they’re referring to here are the hundreds of peoples, like the Assyrians and Babylonians, that they have outlasted across the 3000+ years since they became “Israel”.