In Mathura, both Krishna and Balarama were initiated by Gargamuni in the Gayatri mantra> Later They went to live under the care of Sandipani Muni who instructed Them in all the Vedic arts and sciences in sixty-four days and nights especially in military science, politics and spirituality. As an offering (guru-daksina) to Their teacher, They recovered his son from death. Although God does not need instruction from anyone else, Lord Krsna and His brother set the perfect example : one must accept instruction from and serve a bona-fide spiritual master to advance in spiritual life.
For the next eighteen years, They continued to live in Mathura halting the impending threat of many demonic kings. Later in Their pastimes Lord Balarama married a princess named Revati. Lord Krsna married many queens, the foremost among them being the extraordinarily beautiftil Queen Rukmini. (See Sri Rukmini website for the story of Their marriage). Both Krishna and Balarama established Their palaces in Dvaraka off the coast of western India,
where They enjoyed married life for many years. Although They were married, Lord Krsna and Lord Balarama exhibited the quality of detachment from material life perfectly.
When They were about ninety years old, the great world war of Kuruksetra took place. This climactic battle brought together all the major world leaders. Lord Krsna took the role of a charioteer on the side of the pious Pandavas, while Lord Balarama refusing to participate went on a pilgrimage tour thereby blessing the entire land of India.
At the start of the war, Lord Krishna displayed His stupendous Universal Form delivered His famous message known as the Bhagavad-gita, literally the Song of God. This Song contains the essence of all knowledge having been spoken by the Supreme Lord Sri Krishna Himself. This war concluded with the destruction of the demonic kings and the reinstatement of the righteous Pandava princes.
Having completed Their mission, Balarama and Krsna resumed Their life in Dvaraka where They spent some thirty-five more years before ending Their earthly manifest activities The foremost description of Lord Krishna's activities occurs in the Srimad Bhagavatam, literally "the Beautiful Book of God."