As the prophet Zechariah proclaims the greatness of Jerusalem's mourning, he says:

¹²“All Israel will mourn, each clan by itself, and with the husbands separate from their wives. The clan of David will mourn alone, as will the clan of Nathan, ¹³the clan of Levi, and the clan of Shimei. ¹⁴Each of the surviving clans from Judah will mourn separately, and with the husbands separate from their wives. —12:12-14 (NLT)

This is a strange collection of named clans. Judah is broken down into separate clans, including the clan of David named separately. Levi is named together as a clan; and then both Nathan and Shimei are named. This is not the list that would expect upon hearing the phrase "the clans of Israel." Why are these particular clans named? Levi, Judah and David are well known; who are Nathan and Shimei?