The Grand Carriage is the main transportation vehicle for the Sranten dynasty who currently rules Yzel, but was in service long before they took over the nation. 
Originally, the Carriage was constructed for the Zhouhang dynasty as a show of the monarchy's wealth and status. The Zhouhang became well known for their extravagance and luxury taste, particularly close to the fall of the dynasty when many people thought the opulence was far too much and draining to the nation. The Sranten taking over was partly in reaction to this and the new dynasty did away with a good deal of the previous rulers' items. However, the carriage remained. 
When it was first built, the vehicle was twice as long as a normal carriage and about half again as tall. The wheels contained gold inlay in the wood and intricate carvings. Each side panel depicted a victory or some other accomplishment of the dynasty's members and the roof was done in gold tile. The interior of the carriage was equally as opulent, with velvet seating, small marble statues, and soft carpets underfoot. 
Upon taking control of the country, the Sranten also gained the carriage. Rather than have it destroyed outright, they removed the outer paneling and replaced it with scenes of their own victories, although done in a more toned down style. The roof was replaced with tiles containing gold designs rather than entirely composed of gold and the wheels were reinforced to make them more utilitarian instead of decorative and needing constant repair. 
Their decision to repurpose the carriage rather than destroy it and create a new one was a point of contention between Luan Sranten and his son, Kaelo Sranten I. The latter believed that using it in this way would make the transition smoother and that the monarchy needed to be slightly set apart from the nobility. However, Luan wanted everything destroyed. Their compromise was the redesign seen today.