Nimbarka (Sanskrit: श्री निम्बार्काचार्य, Telugu: నింబార్కాచార్య Śrī Nimbārkācārya), is known for propagating the Vaishnava Theology of Dvaitadvaita, duality in unity. According to scholars headed by Prof. Roma Bose, he lived in the 13th Century, on the assumption that Śrī Nimbārkācārya was the author of the work Madhvamukhamardana. According to Nimbārka Sampradāya however, Śrī Nimbārkācārya appeared over 5000 years ago, in the year 3096 BCE at the time when the grandson of Arjuna was on the throne. He hailed from the present-day Andhra Pradesh, in South India.

Nimbarka's date is subject to much controversy. Although current research and scholarly consensus centres on a date somewhere just before Sankaracarya, in general scholars have not been able to come to a unilateral conclusion.

Dr. Bhandarkar has placed him as a philosopher after Ramanuja and has maintained his demise date as 1162 AD. Some hold that he is dated around 13th Century. However, Dr. S.N.Dasgupta dated Nimbarka to around middle of 14th Century. On the other hand, Dr. S A A Rizvi assigns the date of Circa 1130-1200 AD But Jadunath Sinha, has counted him as a 13th century philosopher, and Dr. Tarachand has held him to be a younger contemporary of Ramanuja.

Swami Ramdas (1884-1963) was a philosopher, philanthropist, and pilgrim. Giving up worldly possessions at a young age, he became a wandering monk. The inspirational story of his travels throughout India and his message of Universal Love has been presented in several different books and he is regarded by many as a spiritual master.

Vittal Rao was born in Kerala, India in 1884 to Sri Balakrishna Rao and Smt. Lalita Bai. He worked as a spinning master in a cotton mill and in 1908 he married. He experienced difficulties, both in his financial pursuits and domestic life, and seeking relief from his circumstances, he began to chant "Ram" – a name of God. Soon after, his father gave to him a holy mantra to repeat, the Ram Mantra - 'Sri Ram jai Ram jai jai Ram'. Through inner guidance he started adding the 'Om' to each repetition - 'Om Sri Ram Jai Ram Jai Jai Ram' and he found the benefit at least threefold.

He quickly became detached from materialistic pleasures and left on a pilgrimage, taking on the name Ramdas, and living on charity (though he never accepted money). His practice was to view the world as forms of Ram – and thus to see everything that might befall him as the will of Ram. His mantra practice also gradually became a round-the-clock practice.