Connecting tiled terrains

I am starting to create tiled terrain by making multiple terrains separately from Perlin noise. When I put them together and there is a big mismatch in the intersection like shown in a figure bellow:

I was trying to apply weighted averages from one tile height onto another, but it only gives “lined” artefacts. So I was wondering what can be a way to correct this?

Please note, that I am more looking for sensible explanation, rather than some links to Asset Store…

Purchase Stitchscape.

I know your comment said you don’t want a link, but I’m going to assume you’ve searched all over and can’t find a ‘free code’ solution, only partial hints, code snippets, API doc, etc. and you can’t build your solution from those. That’s not a knock on you, that puts you in the same boat as everyone who’s looked into this and decided to go with Stitchscape.

I spend today to follow this tutorial and I managed to get entire procedural terrain working on a “single script” approach:

It only has over 1k lines and can be simply dragged on any game object. Terrain will be generated around camera, when camera moves.