Why Did the Adversaries of Judah and Benjamin Emphasize Their Foreign Origins?

Upon arriving in Jerusalem some time after 538 BCE, the returnees let by Zerubbabel were approached by a group of people whom Ezra 4:1 refers to as "the adversaries of Judah and Benjamin", who requested, "Let us build with you, for we worship your God as you do, and we have been sacrificing to him ever since the days of King Esarhaddon of Assyria who brought us here." Most commentators identify these "adversaries" as the people later known as the Samaritans, although other proposals do exist. An apparently similar group are mentioned in verse 10 as "the nations whom the great and noble Osnappar deported and settled in the cities of Samaria and in the rest of the province Beyond the River". This paper examines the question of their claim to foreign origin: why would they make this claim, rather than claim to be indigenous, YHWH-worshipping, Israelites? Is this claim simply Judean propaganda? Or would the leaders of the "adversaries" have considered it advantageous to be descended from foreign deportees? This question will be examined in light of Assyrian deportation policies and the archaeological record, and we will propose a solution that might shed light on the "ethnogenesis" of the Samaritans during the Persian Period.