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