The Marathas, I believe, are an important Indian dynasty who are not studied well in school curriculum. They are quite understated outside Maharashtra. In sheer size of the people controlled in their empire, they would rank among the world’s top 10. They deserve a place in world history, not just Indian history. 

The speed of their conquests are mindboggling. Let me show one example how quick they were fighting. In 1737, they attacked Delhi in north India and won the Mughals. In 1738 they won Bhopal in central India. In 1741, they attacked around Hoogly [near Calcutta] in east India and won the Nawab. In 1742, they sieged Tiruchirapalli in south India and defeated the Nawab of Carnatic. All of these cities are 1000km+ from each other and quite far away from Maratha home in Pune/Raigad.  I don’t know of any other empire in history who fought in such a huge arc, in this short a time and still won. 
By 1758 they captured Lahore and were winning battles as far away as Afghanistan’s Durrani empire [Battle of Peshawar (1758)] – some 2000 km away from their capital. In parallel, they were setting up a promising kingdom some 3000km away in Tamil Nadu – one of the rare Indian empires to include the state [Thanjavur Maratha kingdom]. The Marathas left a key cultural mark in Tamil Nadu in places like Thanjavur, Vellore, Gingee and Tiruchirappalli. 
Inbetween winning Peshawar and Thanjavur, they were terrorising the “poor” East India Company in Calcutta. The company had to eventually build a big ditch around Calcutta to keep the Marathas out. Maratha Ditch

When I look the Marathas, I see the raw energy of the Mongols – in their speed and brilliance. Like the Mongols there is also a darker side [Bargi] that we sometimes gloss over & that eventually sparked their downfall. Every powerful empire has such a dark side. The Marathas won dozens of battles against a variety of enemies in a very short period. I always ponder the what ifs. What if the Marathas didn’t attempt to fight so many battles at the same time? What if they didn’t provoke the Afghans & the Durannis leading to the Third battle of Panipat?

Marathas v. Peshwas

Marathas are the warrior class from Maharashtra, while Peshwas are the priest class who often served as the Prime Ministers. Peshwa is a Persian word to denote a leader and it was first given to Moropant Trimbak Pingle. Initially the powers were somewhat limited. But, starting from Balaji Vishwanath the Bhat family who were Chitpavan (koknastha brahmins) started controlling the Maratha dynasty. One of the key Peshwas who led to a temporar Maratha resurrection after the defeat in Panipat is Madhavrao I.
The Chitpavans had a very key role in Indian politics. From the same Chitpavan caste came Tilak, Gokhale, Savarkar, Ranade, Nana Sahib [leader in 1857 revolution], Bhave [Gandhi’s spiritual successor] and even Gandhi’s assassin, Godse. 
Even after the Maratha empire died, individual royal houses ruled various parts of central India until India’s independence. Some of the most powerful Maratha royal houses were the Bhonsle [Shivaji came from that], Holkar [ruled Indore], Scindia[ruled Gwalior] and Gaekwad [ruled Baroda]. Many of those dynasties continue to impact the politics of the present day. 

Political Organization

Sivaji had a group of 8 ministers to guide him. Ashta Pradhan. These include Peshwa [Prime Minister], Amatya [Finance Minister], Sumant [Foreign Minister], Sanjeev [Secretary of edicts], Senapati [Commander of the Army], Mantri [Home Minister], Nyayadhish [Chief Justice] and Panditrao [High priest].
These posts were to be appointed by the emperor. Eventually, these posts became hereditary and the Peshwas won far more power than the other minister. 

If I had to provide one adjective to great Indian empires, I would provide grandeur to Maurya, scientific to the Gupta, artistic to the Mughals, exploratory to the Cholas and speed to the Marathas. Even shield of Ahoms and valor of Gurjar pratihara could be a consideration, whatsay?