There are Mesopotamian records that refer to various parallel states. But it's not easy to prove that a particular name refers to a particular area.
(If I'm remembering correctly, we do suspect a particular group mentioned in Mesopotamian records of being Harappan. It's still impossible to prove; you'd want a lot more evidence than "we think it was these guys" before renaming the culture. There is also no particular reason to believe that the Sumerian word for Harappans was related to the Harappan word for themselves.)
(If I'm remembering correctly, we do suspect a particular group mentioned in Mesopotamian records of being Harappan. It's still impossible to prove; you'd want a lot more evidence than "we think it was these guys" before renaming the culture. There is also no particular reason to believe that the Sumerian word for Harappans was related to the Harappan word for themselves.)
EDIT: found it - https://en.wikipedia.org/wiki/Meluhha