San Isidro, officially the Municipality of San Isidro, is a 2nd class municipality in the province of Nueva Ecija, Philippines. According to the 2020 census, it has a population of 54,372 people.

Kapampangan, Capampáñgan, or Pampangan is an Austronesian language, and one of the eight major languages of the Philippines. It is the primary and predominant language of the entire province of Pampanga and southern Tarlac, on the southern part of Luzon's central plains geographic region, where the Kapampangan ethnic group resides. Kapampangan is also spoken in northeastern Bataan, as well as in the provinces of Bulacan, Nueva Ecija, and Zambales that border Pampanga. It is further spoken as a second language by a few Aeta groups in the southern part of Central Luzon. The language is known honorifically as Amánung Sísuan.