Commercial production of mineral oil has started recently in which one of the areas of India, labelled 1, 2, 3 and 4 in the rough map given below:

1. The question asks to identify the area where commercial production of mineral oil (petroleum) started recently (as of 1998) from the labelled map locations. 2. Location 1 is likely in the Krishna-Godavari Basin region (East Coast). 3. Location 2 seems to be in the Mumbai High offshore region (West Coast). 4. Location 3 could represent areas in Assam or the Northeast. 5. Location 4 appears to be in Rajasthan. 6. In the mid-to-late 1990s, significant exploration and discoveries were happening in the Krishna-Godavari (KG) Basin (Location 1) and Rajasthan (Location 4, particularly Cairn Energy's discoveries). Mumbai High (Location 2) and Assam (Location 3) were older producing areas. 7. Commercial production from Rajasthan fields, particularly Mangala, started later (around 2009), but discoveries were being made in the 1990s. KG basin also saw major gas discoveries around this time, leading to later production. 8. Considering 'recently started' in 1998, activity in the KG basin (Location 1) was gaining momentum. Cairn's Rajasthan activities (Location 4) were also significant. Without precise dating, it's hard to definitively choose between 1 and 4. However, KG basin offshore activities were prominent in the news then. If 4 represents the Barmer basin in Rajasthan, significant commercial oil production began later. Let's tentatively select Location 1 (KG Basin) as a region where new production phases were commencing or anticipated around that time.