Raga Poorvi belongs to Poorvi Thaat. It is a Sandhiprakash Raga, and is rendered at dusk, that is the time when the day ends. It uses all seven notes in the ascent and the descent. Rishabh and Dhaivat are komal (flat), Madhyam is both shuddha and tivra while Gandhar and Nishad are shuddha (full). The derivative ragas out of this structure are grouped under the broad head of Poorvi Thaat.
Thaat : Poorvi
Samay : Pre-dawn