The world in 900 AD and the location of Tondo, also known as Lusung
and its neighbors.
Numerous theories on the origin of the name "Tondo" have been put forward. Filipino National Artist
Nick Joaquin suggested that it might be a reference to high ground ("tundok").
 French linguist Jean-Paul Potet, however, has suggested that the River Mangrove,
Aegiceras corniculatum, which at the time was called "tundok" ("tinduk-tindukan" today), is the most likely origin of the name.
The bay area in which Tondo can be found was named Lusong or Lusung, a name thought to have been derived from the
Tagalog word for a large wooden
mortar used in dehusking rice.
 This name was eventually used as the modern name of the entire island of Luzon.