Answer by Balaji Viswanathan:
Here are the 13 great emperors of Bharat (ancient India). I took the size of the territory won and the influence on the people & culture as the measure of the emperor's greatness. I have also included the maps of their territories. We have 9 individuals and two father-son duos (Samudragupta/Chandragupta II and Raja Raja Chola/Rajendra Chola) who formed the most powerful force fields over the nation.
- Emperor Ashoka (304 BC) — he ruled over one of the largest territories (more than 3 million sq. km) among Indian emperors by winning over most local kings. He then had a change of heart and became a pacifist (without which he could have ruled a territory as big as Genghis Khan's). He is the reason for the spread of Buddhism outside India. He is also the the originator of many ideas that have become a part of our present culture — including the wheel in our flag and our national emblem. Ashoka is revered not just in India, but in most parts of East & South-east Asia.
- Raja Raja Chola & Rajendra Chola (10th century AD) – The greatest of Tamil kings and among the best of India – the father-son duo established the Tamil empire in South East Asia. They built 100+ great temples (including the Tanjore Siva temple) that are a part of UNESCO's world heritage site. Unlike other kings of Bharat, they proceeded to extend their influence beyond India and controlled the Indian ocean's trade routes.
- Chandragupta Maurya (340 BC) — the first Indian emperor and the grandfather of Emperor Ashoka. He unified India and brought a strong response to Greek advance into Asia. He used one of India's greatest strategists – Chanakya and devised ways to defeat his emperors through various means. Like Alexander, he started winning major battles when he was just 20, and recaptured the territories captured by the Alexander's troops east of Iran.
- Samudragupta & Chandragupta II/Vikramaditya (4th century AD of Gupta empire) —– The great Gupta king who has never lost a battle in his whole life. Samudragupta and his son Chandragupta II ushered the golden age of India. They instituted a proper currency system through his minted gold coins. Under their rule India's science & art reached its peak.
- Krishna Devaraya (16th century Vijayangara Empire) — One of the greatest south Indian kings, Krishna Devaraya consolidated southern kingdoms and pushed back the Islamic advances in the south. He built great temples and is a wonderful patron of art.
- Akbar (16th century of Mughal empire) — The greatest Muslim emperor Akbar ruled over much of north India and was a fair monarch who was instrumental in building a large number of Islamic monuments in the country.
- Ajatasatru (491 BC of Magadha empire) — His name in Sanskrit means one who is feared by enemies or invincible. He ruled at the time of Buddha and Mahavira (founder of Jainsim). He started the process of Indian consolidation/empire building that was then continued by his successors. He ruled over a vast part of North & eastern India.
- Alauddin Khilji (14th century Khilji Dynasty) — One of the greatest warriors in the world of that time, Alauddin is one of the few who had defeated the Mongols at their heights (not in one, but 4 battles). One of the few kings who was able to venture deep into the south (as far as Madurai).
- Shivaji (17th century AD Marata Empire) — The greatest emperor of Western India, Shivaji was a master of Guerilla warfare and presided over 100,000 soldiers at his peak. His warfare methods and a dozen battle victories are simply awe-inspiring
- Pulikesin II (7th century AD Chalukya empire) — Ruling from Vatapi Pulikesi is one of the most feared kings of Southern India. He was brutal and his methods were fierce. He fought with 2 of the best emperors in India – Harshavardana & Narasimhavarma I
- Harshavardana (7th century Vardhana empire) — Harsha was greatest emperor of Central India and consolidated much of central India after the fall of Gupta empire. He blocked the advances of Southern emperors such as Pulikesin into North India. A fair ruler who was greatly respected across India and still remembered.
- Narasimhavarman I (7th century Pallava empire) — The emperor who defeated Pulikesi and built one of the masterpieces of Indian architecture – Mahabalipuram. Apart from presiding over a great art civilization in South India, he also influenced the direction of Sri Lanka.