However, their leader Alduin grew prideful of his unique position and became a tyrant, so his Nord subjects rebelled against the dragons in what was known as the Dragon War.

Source: https://gamerant.com/elder-scrolls-dragons-lore-facts/

While the main goal of The Elder Scrolls 5: Skyrim is for the Dragonborn to defeat an ancient dragon named Alduin, players also have plenty of opportunities to seek out side quests and complete them for unique rewards.

Source: https://gamerant.com/skyrim-the-wolf-queen-awakened-quest-guide/