is a comprehensive manual of Buddhist practice that also contains an overview of the Abhidhamma. This text remains one of the most popular Abhidhamma influenced texts in Theravada. Sri Lankan Theravādins also composed shorter introductory manuals to the Abhidhamma. The most popular and widely used of these remains the Abhidhammatthasangaha (Compendium of the Topics of the Abhidharma) by Anuruddha (circa 8th to 12th century). A further period of medieval Sri Lankan scholarship also produced a series of texts called the sub-commentaries (which are commentaries to the commentaries). Abhidhamma remains a living tradition in Theravāda nations today and modern Abhidhamma works continue to be written in modern languages such as Burmese and Sinhala. Abhidhamma studies are particularly stressed in Myanmar, where it has been the primary subject of study since around the 17th century. One of the most important figures in modern Myanmar Buddhism, Ledi Sayadaw (1846–1923), was well known for his writings on Abhidhamma (especially his commentary on the Abhidhammatthasangaha, called the Paramatthadipanitika). Sarvāstivāda Abhidharma The most influential Indian Abhidharma tradition was that of the Sarvāstivāda Vaibhāṣika school, which was dominant in North India, especially Kashmir and also in Bactria and Gandhara. This is the Abhidharma tradition that is studied in East Asian Buddhism and also in Tibetan Buddhism. Like the Theravada Abhidharma, the Sarvāstivāda Abhidharma Pitaka also consists of seven texts, but they are quite different works, unlike the Sarvāstivāda Agamas, which are very close, often identical, to the suttas of the Theravada Sutta Pitaka. According to Frauwallner however, the two Abhidharma collections share an "ancient core", which is basically an early doctrinal list of dharmas. The core canonical work of this school, the Jñānaprasthāna ('Foundation of Knowledge'), also known as Aṣṭaskandha or Aṣṭagrantha, was said to be composed by master Kātyāyanīputra. This became the basis for the Abhidharma Mahāvibhāṣa Śāstra ("Great Commentary"), an encyclopedic work which became the central text of the Vaibhāṣika tradition who became the Kasmiri Sarvāstivāda Orthodoxy under the patronage of the Kushan empire. Despite numerous variations and doctrinal disagreements within the tradition, most Sarvāstivāda-Vaibhāṣikas were united in their acceptance of the doctrine of "sarvāstitva" (all exists), which says that all phenomena in the three times (past, present and future) can be said to exist. Another defining Vaibhāṣika doctrine was that of simultaneous causation (sahabhū-hetu). In addition to the core Vaibhāṣika Abhidharma literature, a variety of expository texts or treatises were written to serve as