Northern-Zhōu / Suí 北周–隋 dynasty Buddhist scholar-monk and one of the leading exegetes of the early Suí state-Buddhist establishment. Lay surname Wáng 王; native of Sāngquán 桑泉 (in the Hédōng region, modern southern Shānxī). Lifedates 516–588 (Suí Kāihuáng 8, age 73, per the Yínián lù 疑年錄 and the Xù gāosēng zhuàn 續高僧傳, T50n2060). Sometimes called simply Yán 延 or Yántǒng 延統 (“Yán the Patriarch”) in the literature.
Initially a hermit on the Tài-háng 太行 mountain at Bǎi-tī-sì 百梯寺, where he composed his Niè-pán jīng shū 涅槃經疏 commentary on the Mahāparinirvāṇa-sūtra. Later moved to Cháng’ān, where he became an imperial preceptor: at the start of Northern Zhōu Wǔ-dì’s reign he was made guó-tǒng 國統 (“State-Patriarch”), the highest Buddhist administrative office. When the emperor moved to abolish Buddhism in 574, Tán-yán remonstrated forcefully but unsuccessfully; he then withdrew to the Tài-háng mountains. After Suí Wén-dì’s accession, he came back into court favor — shaved the heads of his disciples himself, ordained 4,000 monks at Wén-dì’s request, founded the Yán-xīng-sì 延興寺, and in Kāihuáng 6 (586) administered the eight precepts to the emperor and the assembled court officials.
Author of major commentaries on the Nièpán jīng (now lost), the Bǎoxìng lùn 寶性論, the Shèngmán jīng 勝鬘經, and the Rénwáng jīng 仁王經. In the Kanripo corpus he is the credited author of KR6o0111, the Qǐxìn lùn yìshū 起信論義疏 (X45n755) — a brief, elegant Sui-period commentary on the Awakening of Faith whose attribution is occasionally disputed but accepted by the Wànxùzàngjīng tradition. Teacher of 智愷’s student-line and other Sui-period scholars; the connection makes Tányán’s authorship of an early Qǐxìn lùn commentary historically plausible.
Sources: DILA Buddhist Person Authority A001779; Xù gāosēng zhuàn T50n2060; Fóguāng dàcídiǎn 6230; Yínián lù 49.