It is the industrial revolution in Equestria. New buildings of gray stone invade the surrounding forests while pillars of iron pump charred smoke into the dense sky. By this time in Early Equestrian history, griffon trading is much more sought after than Saddle Arabian imports, leading to economic booms in Baltimare, Fillydelphia, and Manehatten. With this new source of cheap production, mass crowds of earth ponies are sent into the industrial cities along with the immigrants from neighboring countries.
*Featured in EQD's drawfriend stuff*