The tenth mandala (10.90) of Rig Veda states:
ब्राह्मणोऽस्य मुखमासीद बाहू राजन्य कृतः।
ऊरु तदस्य यद्वैश्य पद्भयां शुद्रो अजायत॥
This verse describes the perfect human being called "The Purusha". From his mouth came Brahmanas, from his arms came Kshatriyas, from his thighs came Vaishyas and from his feet came the Shudras. This division is called "Varna" system, often misinterpreted as caste system.
Time and again the Varna system created in this verse is misunderstood, misrepresented and many a times mistranslated to show that the ancient Vedic culture (on which present Hinduism is based on) favored evils like untouchability, oppression of weaker classes, evil caste system. The verse, in no way, distinguishes men suggesting one being superior than other. This division is definitely not based on birth. So the whole concept of son of a brahmin should be a brahmin and son of a shudra should be a shudra is absurd. The varna or characteristic comes from karma(deeds) and not by birth.
The Purusha sukta also emphasizes on Yagya(sacrifice) as being the starting point in which the Purusha is used as a means (sadhana). Yagya or the act of sacrifice plays a very vital role in our ancient scriptures. While performing a yagya, the arms does the act of sacrifice (kshatriyas sacrifices the love for life and near and dear ones to protect others), mouth enchants the mantras (brahmins speak for betterment, for imparting knowledge to others), the sitting posture (lap) carries the materials to be used in the yagya (the vaishyas doing the cultivation and producing grains for others) and feet supporting the entire body of the Purusha (shudras assisting others so that they can perform their duties well). The Rig veda states that the devas (Gods) perform the Yagya and the Purusha is being used a means to perform the yagya.
The Vedic culture kept the greater part of the Indian subcontinent intact and bound by faith of belief for a very large span of time. Any social system that binds a large chunk of people always play a pivotal role in politics and path of progress for the society. But the systems fail to stay strong when they are not able to accept changes. "The only constant thing is the world is change". Any belief system should remember and imbibe this eternal truth for its growth.
Vedic period comprised of people leading their lives as prescribed in the vedas. With the progress of time and misrepresentation and wrong interpretation of the vedas, the practice of discrimination against weaker sections of society started. The yagyas became more like a promotion activity of the ruling class. The brahmins used to assist and coordinate yagyas actively only because kings used to give donations and gifts to them. Brahmins thus prospered and society started looking down upon shudras. The society started 'assigning' varnas based on birth rather than profession.The vedic period that started somewhere in 5000 BC begin to lose its grip and luster by mid 500 BC.
The advent of Buddhism in 6th-5th century BC in India changed a lot of things. Buddha's teachings led to adoption of a lifestyle which was very different from Vedic culture. Buddha censured any kind of violence and also preached the dharma of forgiveness and peace.
You can read in detail about various stories of Buddha with my sketches in post:
Buddha: the celebrated Guru
The age-old practices of vedas were being challenged. Some yagyas conducted by kings used to involve animal sacrifices. Buddha desisted violence and he also pitied and supported the weaker sections of the society. The shudras, who were already being exploited by those using corrupted interpretation of Vedic lifestyle, were supported by Buddha. The advent of Mahavira and Jainism also had the similar effect. The ascend of shudra born Mahapadma Nanada (4th century BC) to the throne of Magadha, insult of a brahmin Chanakya in Nanda court were some of the examples.
To know more about Chanakya please visit another post:
Chanakya : The God of Political Science
After the establishment of the Maurya kingdom by Chandragupta Maurya (Chandragupta Maurya: The first emperor of united India) the greater part of India was united into a single great kingdom. The power of vedic lifestyle which was fading could not hold the society together so the might of the king and expansion of his power brought everyone under one umbrella. In such a scenario, the belief system adopted and supported by the king would play a very important role, as the subjects would also tend to follow the same belief system. Chandragupta Maurya and then later his descendant Ashok focused on uniting the Indian subcontinent under one power and under one belief system.
King Ashok is considered to be the greatest king to rule India. (To know more about Ashok, please read my post: Ashoka - The greatest king of Indian history ) Ashok initially followed the policy of expansion of the kingdom through blood and war. However, having being inspired by the teachings of Buddha, he left the path of violence and started promoting Buddhism. The extent of his kingdom was vast. The influence he could have over his subjects was voluminous. With the support of the policies of King Ashok and later Mauryan kings, Buddhism prospered and various Buddhist stupas and monasteries were established throughout the length and breadth of Indian sub-continent.
The later Mauryan kings however, were not as effective as Ashok. The later descendants of Mauryan dynasty failed to hold the uprising and revolt of the kingdoms won by Chandragupta and Ashok. As a result, disintegration started and various kingdoms like Ashmaka(present Maharashtra), Kalinga(Orissa), Madra, Kekaya, Gandhar(in present Pakistan) declared independence from the Magadha empire. On top of that, the Mauryan kings ruling Pataliputra (Patna, Bihar) were supporting and appeasing Buddhism while neglecting the age old Vedic lifestyle.
There was a growing sense of resentment among the people favoring old ways of Vedic lifestyle. All this resulted in a shocking event during the reign of Brihadratha, the last Mauryan king in 185 BC.
Pushyamitra Shunga was the commander-in-chief of Brihadratha's army. He was a brahmin and a strong follower of Vedic lifestyle. It is said that he was extremely unhappy with the way Brihadratha was running his kingdom. He was also not happy with the appeasement policy towards Buddhism. The appeasement and inaction of the Magadha not only led to independence of provinces but also led to military campaigns by foreign invaders. The Macedonian kings (Indo-Greek) who were vanquished by Chandragupta and who never dared to enter Indian sub continent during the reign of Ashok, attacked and captured a large portion of North western region (Gandhar, Kekaya, etc). It is said that Menander-I, also known as Milind, was ruling Sakala (Sialkot) at that time.
The Macedonians were marching against different Indian states including the Magadha empire. Some of the Indo-Greek kings were followers of Buddhism so there was a general sentiment that the king of Magadha Brihadratha would hardly show any resistance.
Frustrated by the lethargic attitude of the king, decline of the Vedic culture and favoritism of Buddhism above Vedic beliefs, Pushyamitra and his army started believing that Brihadratha is not fit to rule. In a fit of rage, one day Pushyamitra Shunga killed the king Brihadratha while he was inspecting the army. This was the advent of Regicide in Indian history.
Pushyamitra Shunga killing Brihadratha, 185 BC
Not only the Indo-Greek kings, Pushyamitra Shunga did also fight many wars with the neighboring Shatavahanas and Kalingas. However, the Shungas were able to defend the territories of Magadha against invaders.
The Shunga Empire (185 BC-73 BC)
Pushyamitra Shunga is often portrayed as villain in some Buddhist texts as he allegedly destroyed many stupas and monasteries because of his hatred towards Buddhism. Some other sources including some Buddhist sources, however, suggest that he was quiet tolerant towards Buddhism. The only thing he promoted was long lost ways of Vedic lifestyle. But by that time, the vedic culture was already corrupted. The culture of "Samanta" (Nobility) started and discrimination of varnas like Shudras started.
However, Shunga empire did contribute a lot in the cultural and literary growth of our country. The third and most famous commentary on compilation of grammatical rules of Sanskrit language(written by an ancient acharya named Panini) was done by an acharya known as Patanjali during this period. This commentary was called "Mahabhashya".
Much of that era must have been documented. So much so that son of Pushyamitra, Agnimitra was a chief character in a play written by Kalidasa 450 years later. The play "Malavikagnimitra" by Kalidasa tells the story of king Agnimitra smitten by the beauty of a royal courtesan dancer named Malavika by just looking at the painting. He organizes a dance competition among the best of royal dance trainers just to get a chance to see Malavika in person. On a parallel track there is a story of a military expedition of Magadha towards Ujjain. While the queens of king try to keep Malavika away from the sight of the king, Agnimitra finally is able to meet Malavika with the help of his jester. Furious queen imprisons Malavika only to know that Malavika is actually a princess of Ujjain. Acknowledging the royal lineage of Malavika, the queen agrees for the marriage between king and Malavika. In the end Malavika and Agnimitra marry.
Malavika and Agnimitra Shunga from Kalidasa's play
So, the credit for keeping the Vedic lifestyle alive, keeping the foreign forces at bay and for the immense contribution towards art and literature, Shungas will always be remembered for giving a glorious past to our country between 185 BC and 73 BC. The main blot on the names of Shunga is the way they usurped the throne. The culture of regicide started by Shunga was continued for many generations later and Shungas line itself ended when the last Shunga king was killed by his own minister.