MIMAROPA is an administrative region in the Philippines, designated as Region IV-B. It is one of two regions in the country having no land border with another region, the other being Eastern Visayas. The name is an acronym combination of its constituent provinces, which are: Mindoro (divided into Occidental Mindoro and Oriental Mindoro), Marinduque, Romblon and Palawan. The region is also formally known as the Southern Tagalog Islands.
The region was part of the now-defunct Southern Tagalog region until May 17, 2002. On May 23, 2005, Palawan and the highly urbanized city of Puerto Princesa were moved to the region of Western Visayas by Executive Order No. 429. However, on August 19, 2005, then-President Arroyo issued Administrative Order No. 129 to hold the earlier EO 429 in abeyance pending a review.