The Elder Scrolls Online
The Bosmer are smaller than their Altmer brethren. Nimble and quick, they are supreme hunters, guides and masters in sneaking and thievery. They revere nature and their forest home.
When the Aldmer abandoned their home of Aldmeris and landed in their new of Tamriel, most of them stayed in the Summerset Isles, but others ventured further to find where they belonged. They eventually ventured into Valenwood, and set their eyes upon the unconstrained and lush jungle and they understood that they could not change the wood for them to inhabit, instead choosing to adapt to their new surroundings.
These new Mer became the Bosmer, also known as Wood Elves, Bolche, or Tree-Sap people.
This transformation is credited by the Bosmer to Y’ffre the Forest God. In the doctrines, a pact was made to never kill, injure or eat any of the vegetation of their new residence as abiding appreciation. This became known as the Green Pact, or the Treaty of Frond and Leaf.