You need to brush up on geography. Between China and India sits the tallest and longest and widest mountain range on the globe...the Himalaya’s.
For thousands of years of past history, the only land access to India was the 2 passes...the Khyber pass and the Karakoram pass. These are located in NW direction from India, The Mongols & Arab invaders used those routes 13 centuries back.
China is located in North-East direction from India.
You be wrong...