Final answer:
The Himalayan Mountains serve as a natural barrier between India and the rest of Asia, formed by the tectonic collision of the Indian and Eurasian Plates.
Step-by-step explanation:
The physical barrier that lies between India and the rest of Asia is the majestic Himalayan Mountains. These significant mountain ranges act as a natural barrier separating India from China, and they are considered sacred by some of the local populations. The formation of the Himalayas is the result of the tectonic collision between the Indian Plate and the Eurasian Plate, a process that started about 70 million years ago and continues to this day, with the ranges still rising in elevation annually.