Where does “𒐞” come from?

𒐞 (Akkadian) comes from Sumerian 𒐞, from Sumerian 𒌋, from Akkadian 𒀀 — water; heir.

Ancestry of “𒐞”, step by step

Step	Language	Word	Meaning
1	Sumerian	𒐞	six hundred, 600
2	Sumerian	𒌋	breach, hole
3	Akkadian	𒀀	water; heir