In ancient India, before 1947, several invasions took place through different routes. These invasions were significant in shaping the history and culture of the Indian subcontinent. Below, we will discuss the major routes through which invaders came to ancient India.

Northwestern Route:
- The northwestern route was one of the most frequently used routes by invaders due to its proximity to Central Asia and the fertile Indus Valley.
- The region was accessible through the Khyber Pass, which served as a gateway for many invaders.
- Invaders like the Aryans, Persians, Greeks, Kushans, Huns, and Turks entered India through this route. Notable among them were Alexander the Great and Mahmud of Ghazni.

Eastern Route:
- The eastern route was used by invaders from Southeast Asia, particularly from Burma (now Myanmar).
- These invaders, known as the Ahoms, entered India from the east and established their kingdom in Assam.
- They had to cross rivers such as the Brahmaputra and its tributaries to reach India.

Western Coast:
- The western coast of India was another route used by invaders.
- The Arabs were the first to use this route for trade and later for invasions.
- The Arabs, Turks, and Persians entered India through the western coast and established several dynasties, including the Delhi Sultanate and the Mughal Empire.

Maritime Route:
- The maritime route was used by invaders from far-off lands, including the Arabs, Persians, and Europeans.
- The Arabs and Persians used this route for trade and later for invasions.
- The Europeans, particularly the Portuguese, Dutch, French, and British, entered India through this route during the colonial era.

Central and Southern Route:
- The central and southern regions of India were relatively protected by natural barriers such as the Vindhya and Satpura mountain ranges, making invasions through these routes less frequent.
- However, there were instances when invaders from the north, such as the Mauryas and Mughals, expanded their empires to central and southern India.

These routes were crucial in facilitating cultural exchanges, trade, and the spread of various dynasties in ancient India. They played a significant role in shaping Indian history and the diversity of its culture.