How To Be Sure That Ijma Aur Tawatur Of Sahaba Actually Reached Faroff Lands
There is no such place in the record that only companion went somewhere. All the lands which the companions conquered received their unanimous and perpetual set of beliefs and practices from a large groups of them, and this tradition carried on from generations to generations till date. These lands were interconnected and the people used to travel in between frequently.
Furqan the point that Ghamidi sahab makes is that everything that’s part of religion has been transmitted to us through ijma and tawatur. Every companion of Prophet SAW taught the same practice regardless of where they went. Even if people learnt from a single companion in a given region, collectively we find the same practice in every region. If we find a practice only transmitted by a certain companion only (which I’m unaware of any) then that practice won’t fulfill the requirement of ijma and tawatur and hence it won’t be categorized as part of religion.