This is the concluding part of the series on Pataliputra

The last Mauryan emperor, Brihadratha, proved to be weak and ineffective and lost power in 185 BC — a victim of internal unrest.

The Shunga dynasty took over and ruled for about 100 years, adding their own monuments to the growing collection at Sanchi.

The city’s fate over the next 400 years is unclear, but in about 320 AD, another family emerged to restore Pataliputra to its former glory — the Guptas.

At one point, the Guptas ruled most of India’s east coast almost as far as Tamil Nadu in the south as well as the traditional territory of Magadh.

But the glory days of Pataliputra ended with the Gupta dynasty.

By the end of the 4th century, Pataliputra was grand enough to impress a traveller from the sophisticated culture of China. The writer Fa Hien visited the city during the reign of Chandra Gupta II (380-415 AD), and was speechless in admiration.

He wrote: “The royal palace and the halls in the midst of the city, the wall and the gates with their inlaid sculpture work seem to be the work of superhuman spirits.”

But when Hiuen Tsang, another Chinese traveller, visited the city in 637 AD, he found heaps of rubble where monasteries, temples and shrines once stood.

“Once upon a time,” he wrote, “there must have been hundreds of these buildings. Now, only two or three of them are still standing. All that is left, to the north of where the palace was and near the Ganges, is a small town consisting of about 1,000 houses.”

Sometime between the 5th and 7th century AD, Pataliputra was destroyed.

There are several theories on what led to its destruction. Probably, the final destruction was probably caused by a catastrophic flood in around 575 AD. But it seems that a huge fire may have also played a major part — archaeologists have found ash and traces of burnt timber during excavations.

Geologists have speculated that the fire may have been started by an earthquake, because the city is near the edge of a tectonic plate that carries the Indian subcontinent. But the ashes may also have been left by invaders.

For more than a century, the Guptas and their neighbours were threatened by a tribe from Central Asia — the Hepthalites, or White Huns, who invaded northern India during the reign of Skanda Gupta (455-67 AD).

A retaliatory attack on the invaders early in the 6th century brought devastation to Pataliputra when the Huns sacked the city — perhaps they set fire to the wooden structures. By the middle of the 6th century, the Huns controlled most of the Guptas’ territory.

Their mere presence north of the city must have disrupted the flow of trade on which the empire’s wealth was based. The resulting loss of financial power may have ignited social and political tensions among the empire’s rulers, leading to internal disputes among the different factions.

After the death of Skanda Gupta, several different lines of succession developed, which suggests that the royal family fell out over who should take power. If so, this magnificent city may have received its death-wound in the chaos of a civil war.

Pataliputra may, in fact, have died a slow death because of continuous internal strife. With it, died the remains of a great culture and perhaps one of the greatest examples of town design with stone and wood.