When did this occur?
Radak #1: It was in Chizkiyah's 14th year, when Sancheriv came to Yerushalayim and heard that Tirhakah Melech Kush left [Kush] to fight him, and Sancheriv went to fight with Egypt and Kush 1 . He returned with the captives to Yerushalayim. Earlier that year, he sent Tartan to Ashdod, and he conquered it. Yeshayah prophesized that just like he conquered Ashdod, so he will conquer Egypt and Kush.
Radak #2, Malbim: Some say that he sent Tartan to Ashdod three years before he came to Yerushalayim. They learn from "Shaloshah Shanim Os u'Mofes Al Egypt v'Al Kush 2 " (3).
Bereishis 2:10-14 implies that Kush is in Asia. If so, one who goes from Egypt to Kush must pass by Eretz Yisrael first! Rather, this Kush borders Egypt; refer to Shemos 7:27:151:1*.
Who is "Sargon"?
Radak, Malbim (from Sanhedrin 94a): He is Sancheriv. He had eight names 1 .
Sanhedrin 94a: His other names were Tiglas Pil'eser, Piln'eser, Shalman'eser, Pul, Sargon, Osnapar, Raba, v'Yakira (Rashi; Gra - Pul, Tiglas Pil'eser, Tiglas Peleser, Tilgas Pilne'eser, Tilgas Pilneser, Shalman'eser, Sargon, Osnapar). Sancheriv was not his true name. He is called so because Sichaso Riv (his speech was quarrelsome), or because Sach v'Nicher (he spoke and reviled Hashem).
