The backdrop of the Bhagavad-gītā is about two royal families, the Pāṇḍavas and the Kauravas. The Pāṇḍavas were followers of dharma (righteousness) whereas the Kauravas were opposed to dharma. This royal feud eventually led to a great war where the Bhagavad-gītā was spoken. For more information please see History of the Bhagavad-gītā.