he probably did as he travelled tibet and india extensively. You can also google about roerich's UFO signting...thing is it is supposed to be an important worshipping place for hindus and tibetians. not sure what this illuminati thing is about but its referenced in hindu texts all the time as seat of shiva. In mahabharata if i'm not wrong the 5 brothers leave the earth into space from the lake in front of this mountain.

The illuminati twist to this is interesting, because indians donot think this place to be demonic as the OP suggests but like anything make your own conclusions.