Wali Deccani is often known as the first entrenched and traditionally established classical poet of Urdu Ghazal. His Deewan (Collection of Ghazals) after its arrival at Delhi settled new horizons in the tradition of rekhta-goi in North India as it introduced a new and wonderful way of expressing one's feelings in local vernacular along with regional themes, imagery, allegory, melodious sounds and metaphors. In other words this was the dawn of invading great north India of "mirzeyan (Mughals) and faseehan" by Deccanis/south Indians through art and inventiveness in local language (Urdu/Hindi). Being a challenge to the supremacy of North Indian poets and writers on language and classical poetic tradition of India, it was quite unacceptable for North Indians. The subsequent historians and especially 'tazkara' writers of Delhi like Meer Taqi Meer and Qaem Chandpuri propagated the renowned theory regarding a Persian poet of that time Shah Gulshan's suggestion to Wali to write in local dialect and adopt local themes for his ghazal. This was just to maintain the authority and supremacy regarding use of language and poetical creativity of 'Dehalviat' over 'Deccaniat'. This article presents a research and analysis of this formulated theory.