Some historical dates concerning the the Vietnamese side:
Le Dynasty 1428 (end of Ming occupation of Vietnam) to 1788 (Qing invasion of Vietnam).
Siam-Viet conflict of 1780 (naval battle on the Mekong).
Nguyen Tay-Son Dynasty 1788 to 1802.
Nguyen Dynasty 1802-1945.

The distinction is important if you consider Siam-Viet relation. During the Le Dynasty, Viet expanded South and ended the Kingdom of Champa, bringing Viet closer to Siam. Siam-Viet relation was mostly through extending each influence over Laos. The later part of Le Dynasty had Civil War between many factions.

While technically under Le Dynasty, the Siam-Viet conflict over Cambodia was fought by Nguyen Tay-Son faction. Siam (lead by King P'ya Taksin) backed the founder of Nguyen Dynasty (Nguyen Anh, head of the Nguyen Faction) fought with Tay Son (lead by Nguyen Hue) in 1780. A revolt in 1782 ended P'ya Taksin and Nguyen Tay-Son faction was busy fighting other factions and the Qing army, so both sides were not able to escalate the conflict further.

During the first part of the Nguyen Dynasty (from 1802 to 1858), Viet consolidated their gains over Cambodia: the Lower Cambodia became Viet provinces, the upper Cambodia became a Viet protectorate.

Annie