Complex sentence: Coupled with the horrendous working and living conditions the labour riots that began in 1934, starting with Belize lumber workers and spreading through almost every British colony in the region by 1939, marked the breaking point of the current colonial system in the region.
Split into simpler sentences: Coupled with the horrendous working and living conditions the labour riots that began in 1934, starting with Belize lumber workers and spreading through almost every British colony in the region by 1939. That marked the breaking point of the current colonial system in the region.