Tan-luan was a Buddhist monk who lived during the period of the Northern and Southern Dynasties in China. He is thought to be the founder of Jodo (Pure Land) sect in China.
He was born in Yanmen (present-day Daixian, Shanxi Province, China) close to Mt. Wutai Shan. It is not known when he was born or when he died, but it is thought that he lived from a year in the latter half of the Northern Wei period to the Northern Qi period. He was the First Patriarch of the Five Patriarchs of Jodo sect, and the Third of the Seven Patriarchs of Jodo shin shu (True Pure Land Sect Buddhism).
After Tan-luan became a monk, he read many books including Four Treatise ("Madhyamaka-karika [Fundamental Verses on the Middle Way]," "Dvadasanikaya Shastra [Twelve Gate Treatise]," "Commentary on the Great Wisdom Sutra, " and "Shatashastra [One Hundred Verses Treatise]") by Nagarjuna and his disciples, and the Sutra of the Great Nirvana, to learn about buddhata. However, while he was annotating "Mahsamnipata sutra," he became sick.
He studied the secret art of eternal youth and longevity from Tao Hong-jing in Maoshan and obtained 'Sengyo (Taoist bible).'
On the way back home he met Bodhiruci in Luoyang. Bodhiruci persuaded him that it was Buddhism that contained the true teachings of eternal life, and gave him "Kan Muryoju-kyo Sutra" (Meditation Sutra). Therefore, Tan-luan burned 'Sengyo (Taoist bible),' and was converted to Jodo sect. He kept studying, and became the chief priest of Daigan-ji Temple(大巌寺) in Bingzhou, moved to the Xuanzhongsi Temple in Shibi, then to Yozan-ji Temple (遥山寺) in Mt. Pingyao (平遥山) of Fenzhou, where he died. By Imperial order he was buried at Text Valley (文谷) of West Qinling (西秦陵) in Fenzhou.
"Muryoju-kyo Ubadaisha Ganshoge-chu" (Commentary on Upadeśa on the Sutra of Immeasurable Life) is usually abbreviated to "Jodo ron chu" (Commentary on Treatise on the Pure Land), or "Ojo ron chu" (往生論注), or more simply, "Ron chu" (論註). This is a commentary on "Treatise on the Pure Land" (its formal name: "Muryoju-kyo Ubadaisha Ganshoge" [Upadesa on the Sutra of Immeasurable Life]) written by Tenjin (Seshin) (Vasubandhu).
(To be precise, "Treatise on the Pure Land" itself was the commentary on "Sutra of Immeasurable Life"; Tan-luan annotated the commentary again.)
He argued that in the days of mappo (the end of the Dharma) without a buddha, one could attain nirvana only through Birth in the Pure Land by believing in Tariki (Other Power). At the end of the second volume, he proved that Other Power was the source of everything so logically and explicitly that one would feel as if one was watching the dominoes falling down one after another. The priests who followed him such as Tao-chuo and Shan-dao as well as Genshin, Honen, and Shinran in Japan adopted Tan-luan's logic in their own theories because of its persuasiveness. Most of all, his theory forms the basis of Shinran's doctrine.
"San Amida butsu ge" (Hymns in Praise of Amida Buddha) is a tribute to Amida tathagata in poetic verse. He declared that one should discard the Difficult Path and take the Easy Path where one entrusts everything to Amida's power described in the Original Vow. Thus he established the doctrine of Jodo sect.