The Magadha Mahajanapada was naturally protected because it was surrounded by which two rivers (on its northern and western sides)?

The Magadha Mahajanapada was bounded by the Ganga river in the north and the Son river in the west, which gave it natural protection and other advantages.

About the location of Magadha:

• It covered the present-day Patna, Gaya and Nalanda districts of southern Bihar.
• To the north lay the Ganga, and to the west the Son.
• To the south were the hills and forests of the Chhota Nagpur plateau (Vindhya hills), and to the east was the Champa river (bordering Anga).
• Its early capital was surrounded by five hills, and its later capital, Pataliputra, was located at the confluence of the Ganga and the Son, which acted like a "water fort" (jaladurga).

Advantages of Magadha (NCERT):

• The rivers were important for transport, water supply and making the land fertile; the alluvial soil of the Ganga plain was very productive.
• The forests in the region provided elephants, which were used in the army.
• Rich deposits of iron ore in the nearby areas (present-day Jharkhand) were used to make tools and weapons.
• Trade along the Ganga brought wealth.
• Ambitious and powerful rulers, such as Bimbisara, Ajatashatru and Mahapadma Nanda, used these advantages to expand the kingdom.

Dynasties of Magadha:

• Haryanka dynasty: Bimbisara, Ajatashatru, Udayin.
• Shishunaga dynasty.
• Nanda dynasty.
• Maurya dynasty.
• Magadha became the centre of the first great empires of India.

About the Son river:

• It rises near Amarkantak in Madhya Pradesh and flows north-east to join the Ganga near Patna.
• It is one of the largest southern tributaries of the Ganga.
• The Bansagar Dam is built on it.

Why not the other options?

• ✗The Ganga and Yamuna meet at Prayagraj, far west of Magadha.
• ✗The Gandak and Kosi are north Bihar rivers.
• ✗The Narmada flows west to the Arabian Sea.