Scotland became a unified kingdom in 843 under King Cináed I, who united the Scots and the Picts. It would grow in size over time, but the Kingdom of Scotland began in 843.
In 1603 the realms of England and Scotland were united by the accession of James VI to the throne of England. However, it wasn’t until this day in 1707, when the Treaty of Union was passed by the Parliament of Scotland which brought into being the United Kingdom. With this act Scotland lost its independence and there remains a movement to regain it.