Nabû-šuma-iškun, inscribed mdnabû-šuma-iškunun, and meaning "Nabû has set a name", was king of Babylon, speculatively ca. 761 – 748 BC, and ruled during a time of great civil unrest. He came from the Bīt-Dakkūri tribe, a Chaldean group apparently unrelated to that of his immediate predecessor, Erība-Marduk.

Chaldea was a small country that existed between the late 10th or early 9th and mid-6th centuries BC, after which the country and its people were absorbed and assimilated into the indigenous population of Babylonia. Semitic-speaking, it was located in the marshy land of the far southeastern corner of Mesopotamia and briefly came to rule Babylon. The Hebrew Bible uses the term כשדים (Kaśdim) and this is translated as Chaldaeans in the Greek Old Testament, although there is some dispute as to whether Kasdim in fact means Chaldean or refers to the south Mesopotamian Kaldu.