This is what my attorney in Palawan required from me to progress with buying land, it may help

1. get a copy of certificate of non-encumbrance from the provincial assessor's office to ensure if the property is still in the possession of the seller and to determine if it is not mortgage to anyone;

2. get a barangay certification to determine that the property is owned by the seller;

3. get a copy of public land application from the seller to determine if the property is ready for titling;

if you have these documents, you can proceed to the buying of the property