Prāṇāyāma should begin after mastery of basic Āsana and mental discipline, when the body and breath are stable, and preferably under the guidance of a qualified teacher.
In the system described in the Yoga Sutras of Patanjali, Prāṇāyāma is the 4th limb of yoga. Therefore, it is practiced after: yama, Niyama and Asana
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