Shishunaga (also called King Sisunaka) was the founder of a dynasty collectively called the Shishunaga dynasty. He established the Magadha empire (in 684 BC). Due in part to this bloody dynastic feuding, it is thought that a civil revolt led to the emergence of the Shishunaga dynasty. This empire, with its original capital in Rajgriha, later shifted to Pataliputra (both currently in the Indian state of Bihar). The Shishunaga dynasty was one of the largest empires of the Indian subcontinent.

The Shishunaga dynasty king Bimbisara was responsible for expanding the boundaries of his kingdom through matrimonial alliances and conquest. The land of Kosala fell to Magadha in this way. Estimates place the territory ruled by this early dynasty at 300 leagues in diameter, and encompassing 80,000 small settlements. Bimbisara is contemporary with the Buddha, and is recorded as a lay disciple. Bimbisara (543-493 BCE ) was imprisoned and killed his his and became successor, Ajatashatru (491-461 BCE), under whose rule, the dynasty reached its largest extent.

Licchavi was an ancient republic which existed in what is now Bihar state of India, since the before the birth of Mahavira (b. 599 BC), Vaishali was the capital of the Licchavis and the Vajjian Confederacy. Its courtesan, Ambapali, was famous for her beauty, and helped in large measure in making the city prosperous. Ajatashatru went to war with the Licchavi several time. Ajatashatru is thought to have ruled from 491 to 461 BC and moved his capital of the Magadha kingdom from Rajagriha to Patliputra. The Mahavamsa tells that Udayabhadra eventually succeeded his father, Ajatashatru, and that under him Patliputra became the largest city in the world. He is thought to have ruled for sixteen years. The kingdom had a particularly bloody succession. Anuruddha eventually succeeded Udaybhadra through assassination, and his son Munda succeeded him in the same fashion, as did his son Nagadasaka.

This dynasty lasted till 424 BC, when it was overthrown by the Nanda dynasty. This period saw the development of two of India’s major religions that started from Magadha. Gautama Buddha in the 6th or 5th century BC was the founder of Buddhism, which later spread to East Asia and Southeast Asia, while Mahavira revived and propagated the ancient sramanic religion of Jainism.

Nanda dynasty was established by an illegitimate son of the king Mahanandin of the previous Shishunaga dynasty. The Nanda dynasty ruled Magadha during the 5th and 4th centuries BC. At its greatest extent, the Nanda Empire extended from Burma in the east, Balochistan in the west and probably as far south to Karnataka. Mahapadma Nanda of Nanda dynasty, has been described as the destroyer of all the Kshatriyas. He defeated the Ikshvaku dynasty, Panchalas, Kasis, Haihayas, Kalingas, Asmakas, Kurus, Maithilas, Surasenas, Vitihotras, etc. He expanded his territory till south of Deccan. Mahapadma Nanda died at the age of 88 and, therefore, he ruled the bulk of the period of this dynasty, which lasted 100 years.

In 321 BC, exiled general Chandragupta Maurya with help of Chanakya founded the Maurya dynasty after overthrowing the reigning Nanda king Dhana Nanda to establish the Maurya Empire. The Maurya Empire (322–185 BC), ruled by the Mauryan dynasty, was geographically extensive, powerful, and a political military empire in ancient India. During this time, most of the subcontinent was united under a single government for the first time. The exceptions were present day Tamil Nadu and Kerala. The empire had its capital city at Pataliputra (modern Patna). The Mauryan empire under Chandragupta Maurya would not only conquer most of the Indian subcontinent, defeating and conquering the satraps left by Alexander the Great but also push its boundaries into Persia and Central Asia, conquering the Gandhara region. Chandragupta Maurya then defeated the invasion led by Seleucus I, a Greek general from Alexander’s army. Chandragupta Maurya’s minister Kautilya Chanakya wrote the Arthashastra, one of the greatest treatises on economics, politics, foreign affairs, administration, military arts, war, and religion ever produced in history of the world.

Chandragupta Maurya was succeeded by his son Bindusara, who expanded the kingdom over most of present day India, barring the extreme south and east. At its greatest extent, the Empire stretched to the north along the natural boundaries of the Himalayas, and to the east stretching into what is now Assam. To the west, it reached beyond modern Pakistan, annexing Balochistan and much of what is now Afghanistan. The Empire was expanded into India’s central and southern regions by the emperors Chandragupta and Bindusara, but it excluded a small portion of unexplored tribal and forested regions near Kalinga.

The Maurya Empire was inherited by his son Ashoka The Great, has been described as one of the greatest rulers the world has seen. Ashoka initially sought to expand his kingdom but In the aftermath of the carnage caused in the invasion of Kalinga, he renounced bloodshed and pursued a policy of non-violence or ahimsa after converting to Buddhism. Following the conquest of Kalinga, Ashoka ended the military expansion of the empire, and led the empire through more than 40 years of relative peace, harmony and prosperity. Ashoka the Great’s response to the Kalinga War is recorded in the Edicts of Ashoka, one of the oldest preserved historical documents of Indian subcontinent.

The Mauryan Empire under Ashoka was responsible for the proliferation of Buddhist ideals across the whole of East Asia and Southeast Asia, fundamentally altering the history and development of Asia as a whole. Under Ashoka, India was a prosperous and stable empire of great economic and military power whose political influence and trade extended across Asia and Europe. Chandragupta Maurya’s embrace of Jainism increased social and religious renewal and reform across his society, while Ashoka, on the other hand, embraced of Buddhism. Ashoka sponsored the spreading of Buddhist ideals into Sri Lanka, Southeast Asia, West Asia and Mediterranean Europe. The Lion Capital of Asoka at Sarnath, is the emblem of India. Archaeologically, the period of Mauryan rule in South Asia falls into the era of Northern Black Polished Ware (NBPW). The Arthashastra, the Edicts of Ashoka and Ashokavadana are primary sources of written records of the Mauryan times.

Ashoka was followed for 50 years by a succession of weaker kings. Brihadrata, the last ruler of the Mauryan dynasty, held territories that had shrunk considerably from the time of emperor Ashoka, although he still upheld the Buddhist faith. The Sunga dynasty was established in 185 BC, about fifty years after Ashoka’s death, when the king Brihadratha, the last of the Mauryan rulers, was assassinated by the then commander-in-chief of the Mauryan armed forces, Pusyamitra Sunga, while he was taking the Guard of Honour of his forces. Pusyamitra Sunga then ascended the throne. Pusyamitra Sunga was a Yadava who then took over the throne and established the Sunga dynasty. Buddhist records such as the Asokavadana write that the assassination of Brihadrata and the rise of the Sunga empire led to a wave of persecution for Buddhists, and a resurgence of Hinduism.

Source : Wikipedia