Night elves are an ancient elven race that lives on an island, northwest of the western continent known as Kalimdor. For a whiel they were in seclusion unitl after the Second War when they joined the Alliance.
War of the Ancients
During this time became the corruption of the elves. acting as a god, Sargeras contacted the most powerful night elf, Azshara. He convinced them to open a gateway for Sargeras to bless the whole race. It gave birth to the Highborne, nobles of powerful magic. The Burning legion thus was created. A small sect of Mlafurion Stormrage's druids attacked these blasted demons. As the war pressed on the Ancient guardians aided the night elves and Highborne. The Dragonflights attacked the demons as well. Malfurion eventually closed Azeroth off from the dark titan Sargeras.
The Well of Eternity was full of power which it then imploded triggering the events of the Sundering, a catclysm splitting the supercontinent of Kalimdor. Some night elves and Highborne were sucked under the sea creating the sea serpent humanoid race known as the naga. A Highborne named Dath'remar Sunstrider sailed over the sea to the brand new continent. The night elves settled into their new culture, they lvied clsoe to the former battlefield. When the World Tree Nordrassil was planted it gave the ngiht elves another shot at immortaility. The land around it was known as Mount Hyjal. Dragon Aspect Ysera watched over the tree.
Rediscovery and the Third War
At this time the orcs were arriving in Kalimdor and the night elf race was rediscovered. The orcs planned many lumber projects which greatly offended the night elves. These acts lead to many duels and battles between the two races. Later they put their wrongs aside to kill a more important threat of great evil...a eredar warlock known as Archimonde.
After the war against Archimonde at Mount Hyjal the night elves began to rebuild what remained. The World Tree Nordrassil was forced to be destroyed and lost their immortality. They found a new city known as Darnassus and took the World Tree of Teldrassil under their hands. They tried to regain the forest's purity after the demons invaded. In the absence of Malfurion Stormrage, Priestess Tyrande Whisperwind took over leadership of the night elves and the druid leadership was given to Fandral Staghelm. After all the sacrifices and the attempt to purify the land they joined the Alliance.