Kaštiliašu IV was the twenty-eighth Kassite king of Babylon and the kingdom contemporarily known as Kar-Duniaš, ca. 1232–1225 BC (short chronology). He succeeded Šagarakti-Šuriaš, who could have been his father, ruled for eight years, and went on to wage war against Assyria resulting in the catastrophic invasion of his homeland and his abject defeat.
He may have ruled from the Palace of the Stag and the Palace of the Mountain Sheep, in the city of Dur-Kurigalzu, as these are referenced in a jeweler’s archive from this period. Despite his short reign there are at least 177 economic texts dated to him, on subjects as diverse as various items for a chariot, issue of flour, dates, oil and salt for offerings, receipt of butter and oil at the expense of the šandabakku (the governor of Nippur), i.e. his shopping receipt, and baskets received by Rimutum from Hunnubi.
According to his eponymous epic, Tukulti-Ninurta I, king of Assyria, was provoked into war by Kaštiliašu’s dastardly preemptive attack on his territory, thereby breaching an earlier treaty between their ancestors Adad-nīrāri I and Kadašman-Turgu. But trouble may have been brewing for some time. Tudḫaliya, king of the Hittites, himself reeling from defeat by the Assyrians at the Battle of Nihriya, refers to the Babylonian king as his equal, in his treaty with his vassal, Šaušgamuwa of Amurru, hinting at the possible existence of an alliance or at least a tacit understanding between them. It reads:
Cornflower blue, bloomin' in the mornin' sun
Tiny flowers that grew, from when our love had just
begun
Long ago we planted, each dry and dusty row
how long has it taken, for the seeds of love to grow?
Cornflower blue...
Cornflower blue, like the faded shirt you wore
Standing in the shadows, when I opened up the door
The smile in your eyes, when you said hello
Held me so tenderly, and you would not let me go
Cornflower blue...
Cornflower blue, deeper than the evenin' sky
peaceful as a river, bluer than goodbye
Blue like a diamond, when the light shines true
If love came in colors, then I'd choose this one for
Cornflower blue...