According to our scriptures, seven cities are mentioned to be highly significant for granting Moksham for their residents. Swami Desikan in His adaikalapathu mentioned, “mukthi tharum nagar Ezhil mukkiyamAm kacchi..”. The seven cities of Mukthi are Ayodhya, Mathura, Maaya (Rishikesh,Haridwar and its surroundings), Kaasi, Kanchi, Ujjain and Dwaraka. Here is a detailed Sthala puranam about Maaya Kshetram written by Sri U.Ve. Vidwan Egai Vedantadesikachar Swami.
Sir, my humble submission is that Maya-Kshetram (also) refers to the Mayapur in West Bengal, about a 100 km to the north of Kolkata. There the Ganga divides into a number of branches and cerates 9 islands, hence this Kshetram is also known as Navadweepa. This is considered one of the holiest places in the universe, meant for Mukti and Bhakti. This is the place where many Avataras of Lord Vishnu have appeared in the past, as mentioned in the scriptures.
It may also refer to Haridwar region, but as per my understanding it actually refers to Mayapur in Bengal (Vanga desa)