Theories on the date of the composition of the Gita vary considerably. Some scholars accept dates from the fifth century to the second century BCE as the probable range, the latter likely. The Hinduism scholar Jeaneane Fowler, in her commentary on the Gita, considers second century BCE to be the probable date of composition.  J. A. B. van Buitenen too states that the Gita was likely composed about 200 BCE. According to the Indologist Arvind Sharma, the Gita is generally accepted to be a 2nd-century-BCE text.
Kashi Nath Upadhyaya, in contrast, dates it a bit earlier. He states that the Gita was always a part of the Mahabharata, and dating the latter suffices in dating the Gita. On the basis of the estimated dates of Mahabharata as evidenced by exact quotes of it in the Buddhist literature by Asvaghosa (c. 100 CE), Upadhyaya states that the Mahabharata, and therefore Gita, must have been well known by then for a Buddhist to be quoting it.[note 6] This suggests a terminus ante quem (latest date) of the Gita to be sometime prior to the 1st century CE. He cites similar quotes in the Dharmasutra texts, the Brahma sutras, and other literature to conclude that the Bhagavad Gita was composed in the fifth or fourth century BCE.[note 7]
According to Arthur Basham, the context of the Bhagavad Gita suggests that it was composed in an era when the ethics of war were being questioned and renunciation to monastic life was becoming popular. Such an era emerged after the rise of Buddhism and Jainism in the 5th century BCE, and particularly after the semi-legendary life of Ashoka in 3rd century BCE. Thus, the first version of the Bhagavad Gita may have been composed in or after the 3rd century BCE.
Linguistically, the Bhagavad Gita is in classical Sanskrit of the early variety, states the Gita scholar Winthrop Sargeant. The text has occasional pre-classical elements of the Sanskrit language, such as the aorist and the prohibitive mā instead of the expected na (not) of classical Sanskrit. This suggests that the text was composed after the Pāṇini era, but before the long compounds of classical Sanskrit became the norm. This would date the text as transmitted by the oral tradition to the later centuries of the 1st-millennium BCE, and the first written version probably to the 2nd or 3rd century CE.
According to Jeaneane Fowler, "the dating of the Gita varies considerably" and depends in part on whether one accepts it to be a part of the early versions of the Mahabharata, or a text that was inserted into the epic at a later date. The earliest "surviving" components therefore are believed to be no older than the earliest "external" references we have to the Mahabharata epic. The Mahabharata – the world's longest poem – is itself a text that was likely written and compiled over several hundred years, one dated between "400 BCE or little earlier, and 2nd century CE, though some claim a few parts can be put as late as 400 CE", states Fowler. The dating of the Gita is thus dependent on the uncertain dating of the Mahabharata. The actual dates of composition of the Gita remain unresolved. While the year and century is uncertain, states Richard Davis, the internal evidence in the text dates the origin of the Gita discourse to the Hindu lunar month of Margashirsha (also called Agrahayana, generally December or January of the Gregorian calendar).