While none of his sons survived Jerusalem's fall, Zedekiah was survived by at least two daughters. One of these daughters had recently married an Irish prince of the line of Judah through Zerah. In fact, the marriage took place during (or shortly before) the siege of Jerusalem. Thus, Zedekiah's daughter, who was a descendant of Perez, married a man descended through Zerah. Both had Judah as a common ancestor.
It is not fanciful to adduce that an Irish prince was visiting Jerusalem in the sixth century BC. The ancients were more traveled than many today want to believe, and international relations, complete with ambassadors, protocols, and "diplomatic immunity," were extant as well. Nehemiah 11:24 mentions a certain Pethahiah, who was probably one such ambassador. More importantly, he was "of the children of Zerah, the son of Judah, [and] was the king's deputy in all matters concerning the people."
The word deputy literally means "hand." In modern idiom, Pethahiah was the Persian king's "right-hand man." As strange as it may seem, several generations after Jeremiah's day, there was a highly placed Jew (that is, someone of Judah) in the Persian court whose task it was to look after the Jews in Palestine.
We do not need to read too much between the lines to understand from this scripture that Ireland had diplomatic relations with the Persians, and Pethahiah, possibly of the Irish royal family, was sent to Persia to represent the interests of the Jews in Palestine. That is, the Irish king, himself a Jew in that he descended from Judah, felt responsible for the Jews in Palestine. Since he did not enjoy hegemony over that part of the world, he looked after their interests through a highly placed person—virtually an ambassador—in the Persian court. Even in today's complex world of foreign relations, this technique is a common method through which a leader can exercise a measure of control over an area outside his immediate authority.
Searching for Israel (Part Nine): The Migration of a Monarchy