Vyāsadeva, he writes . . . this Bhagavad-gītā is one of the chapter of Mahābhārata. Mahābhārata means the history of greater India. Formerly Bhārata . . . "India" is given name by the Westerners, but real name is Bhārata, Bhārata-varṣa. This planet was formerly known as Ilāvṛta-varṣa, and later on, after the Emperor Bharata, this planet was known as Bhārata-varṣa. So Bhārata-varṣa means not only India, but the whole planet. At least five thousand years ago it was known as Bhārata-varṣa. Bhārata-varṣa name is there, but it indicates only India. So this Bhagavad-gītā is a chapter of Mahābhārata. Perhaps you know the book Mahābhārata, "Greater Bhārata-varṣa," "The History of the Greater Bhārata-varṣa." That is Mahābhārata.
So the background of this Bhagavad-gītā is that there was worldwide fight, battle, called the Battle of Kurukṣetra. Kurukṣetra, the place is still there. If some of you went to India, might have seen it is near Delhi, New Delhi. The railway station is called also Kurukṣetra. So there was a battle five thousand years ago. The parties were two cousin-brothers, and this Bhagavad-gītā was spoken by Kṛṣṇa, the Supreme Personality of Godhead, Bhagavān. Therefore it is called bhagavān uvāca.
So He is teaching Arjuna bhakti-yoga. Yoga means the means by which you can contact the Supreme. That is called yoga. Another, yoga means linking. So there are many types of yoga system for linking ourself with the Supreme Absolute Truth. The Absolute Truth is realized in three phases: impersonal, localized and personal.