What are the…
Susanchites

These are the inhabitants of Shushan (Susa), who joined other adversaries of the Jews in an attempt to prevent their rebuilding of Jerusalem’s Holy Temple after the Captivity.

The name Susanchites is found only once in Scripture in the King James Version and some other translations (Ezra 4:9 KJV, AMPC, BRG, JUB). The New King James Version says “the people of…Shushan” (Ezra 4:9 NKJV). Other translations say “the men of Susa” or something similar (Ezra 4:9 NASB, LSB, ESV, AMP, etc.).

Rehum the chancellor and Shimshai the scribe wrote a letter against Jerusalem to Artaxerxes the king in this sort:

Then wrote Rehum the chancellor, and Shimshai the scribe, and the rest of their companions; the Dinaites, the Apharsathchites, the Tarpelites, the Apharsites, the Archevites, the Babylonians, the Susanchites, the Dehavites, and the Elamites, and the rest of the nations whom the great and noble Asnapper brought over, and set in the cities of Samaria, and the rest that are on this side the river, and at such a time. —Ezra 4:8-10 KJV