本文擬建議將印度佛教史，分成初期、中期、後期的時代區分。這是基於常出現在世界各地各種史學的三分法。
大體上，日本從明治時代（1868-1912）後期以來，所使用的原始佛教專門用語（最近在國外很少使用，不過近年來台灣、中國大陸等地還在使用，恐怕是日本的用語移植），一般而言會認為它伴隨著各種的夾雜物，所以宜廢掉而稱做初期佛教。初期佛教是從釋尊到根本分裂（第二次結集）乃至阿育王（Aśoka，亦譯作無憂王。約公元前268-232年在位）時代，即從大約公元前五世紀到大約公元前三世紀中葉為止約150年至200年之間的佛教。
中期佛教，由於教團的分裂產生部派佛教，各部派備齊初期經典（包含律藏），鞏固己見，由傑出的諸論師完成許多的諸論書。其後產生大乘佛教，成立了各種初期大乘經典與少數的論書。時間在公元前三世紀中葉到公元後四世紀初約550年之間。
後期佛教，以公元320年為起點。這一年，笈多王朝（Gupta Dynasty）統一全印度，一味地推行道地的印度教（Hinduism），婆羅門諸文化大放光彩，佛教急速地開始喪失民眾的支持，但是佛教的諸傳統仍然部分地、頑強地擴張教線，從大學問寺的繁榮與許多學僧的出現，以及諸學說的發展與確立，或數次的佛教復興活動中可看出。終於在1203年，印度傳統佛教最後的密教道場超戒寺（Vikramaśīla / Vikramaśilā，超岩寺），受到伊斯蘭軍隊的徹底破壞而消滅，印度的傳統佛教終於閉幕。此時期大約900年間之佛教，可稱之為後期佛教。

According to the trichotomy of the historical science everywhere in the world known to us, it is suggested that Indian Buddhism can be divided into the periodization of early, medieval, and latter periods.
Generally speaking, the so-called primitive Buddhism, the terminology used in the late nineteenth century, i.e. in the late of Meiji times (1868 A.D.-1912 A.D.), has seldom been used in foreign countries, while recently it still prevails in Taiwan and Mainland China. Perhaps it imports from Japan. But some people think that this terminology has too complex meanings, so had better be abandoned, and the terminology "early Buddhism" should be a good substitute for it. The early Buddhism covers from 5th century B.C. to the middle of the 3th century B.C., i.e. about 150 years to 200 years.
Next, the medieval Buddhism includes both the sectarian Buddhism and the early Mahāyāna Buddhism. The former created śāstras (Abhidharma), and the latter produced many Mahāyāna sūtras and its śāstras. The medieval Buddhism is defined as a period from the middle of 3th century B.C. to early 5th century A.D., about 550 years in total.
Lastly, the period "latter Buddhism" lasts from 320 A.D. to 1203 A.D., about 900 years in total. During that period, the esoteric Buddhism derived from India, and it was destined to disappear as Indian Buddhism came to an end in 1203 A.D. due to the Islamic troops invasion.