France had colonial possessions, in various forms, since the beginning of the 17th century, but in the 19th and 20th centuries, its global overseas colonial empire extended greatly and became the second-largest in the world behind the British Empire. Including metropolitan France, the total area of land under French sovereignty almost reached 13 million square kilometres in the 1920s and 1930s, 8.6% of the world's land. Known as the ''Belle Époque'', the turn of the century was a period characterised by optimism, regional peace, economic prosperity and technological, scientific and cultural innovations. In 1905, state secularism was officially established.