[muawiyah]

The Samaritans are supposedly Medes/Persians and others with no Jewish ancestry of any kind who were sent to Israel by the Persians to supplement the population of those returned from the Babylonian exile.

[Verginius Rufus]

If the Samaritans were Medes and Persians they would not have a religion based on the Torah and worship of the same God as the Jews.

Reportedly the Assyrian king deported 27,290 Israelites from Samaria and settled new people (according to II Kings 17 from Babylon, Cuthah, Avva, Hamath, and Sepharvaim), but it's likely that the majority of the population continued to be Israelites. Later Jewish sources may be biased against the Samaritans because they wanted Jerusalem to be considered the only center of the true religion.

There's discussion of this question in Go"sta W. Alstro"m, The History of Ancient Palestine (Fortress Press, Minneapolis, 1993), 899-900.