Agglutinative languages (Proto-Uralic is believed to have been) tend to wander off like a road in no time, which has led to a lot of reclassications, changing the branches of agglutinative language trees, and the like.
The extinct ancient agglutinative languages (Sumerian, Elamite, Kassite, and probably the Indus Valley/Harappan tongue) appear to be isolates, but as they’re only known from scripts, and their possibly unknown contemporary related tongues were never recorded, they may have managed to survive.
A gluten native better watch his steppe...
I strongly believe the Sumerian, Elamite, Harappan languages were interreoand they were related to Dravidian languages. So this Alamo Dravidian language tree spread along the sea shore from south India to Sumeria