How to cut my Landscape

Hello

I have a trouble to split my landscape for tiny parts

I have to use real topological data so I got it from Open DB and Imported it to UE4

It was good but thinking about material rendering I realized that the landscape materials blending is not enough for my entire landscape.

What I mean is I want to use multiple materials more than 3; soil asphalt grass mud concrete and so on…

I made all materials for each and blending them by their material instance

and… my UE4 stopped rendering compiling

So I want to split my single landscape into multiple combinations such as mountain, ground, port and so on…

How to divide this single landscape?