Which means there are tons and tons of different things you can layer and change.
This is a broad look at the eastern edge of the continent, the area conquered by Hachigoku. It includes topography, roads, rivers, and vegetation. It's a bit hard to tell, but the lower portions of the map contain jungles (the dark patches), with deciduous forests (light green) dominating the middle and pine forests (dark green) in the north. The islands to the southeast are also part of Hachigoku.
Of course, Hachigoku is a huge empire (it spans from an equatorial zone to the arctic) and its name means "Eight Realms" (or Kingdoms, Countries, Nations... depends on how you view them). There are in fact seven realms (the Empire is considered the 8th, the "whole greater than the sum of its parts"): Chugoku, Hikugoku, Ichigoku, Kitagoku, Mizugoku, Nigoku, and Takagoku.
Chugoku (the "Middle Realm") is the smallest of the realms, consisting of two basins (at times called High Chugoku and Low Chugoku) nestled between the Green Mountains and Iron Teeth Mountains. Its central rivers tumble over cliffs and ravines, and its people, even the most common, have an affinity for the mystical. The Makino are technically the "high rulers" of Hachigoku's heart, but most of their energy is spent governing the Onmyoryo, an Imperial organization overseeing the onmyioji (samurai wizard-priests). Most administrative tasks are delegated to the Nagai in the east, and the Kitsuregawa guarding the southern passes. The Arima clan quietly tends to its forges and temples in the north.
(The symbols on the map below are mon, samurai heraldy, corresponding to their clans.)
Hikugoku (the "Low Realm") is the southernmost realm, excluding the Lightning Isles south of Nigoku proper. It is heavily settled and covered with an ancient network of canals fedding an endless sea of rice paddies in the central lowlands, flanked by deserts to the west and the jungles of the Kinoshita and Kikkawa in the east. The Asano are considered the preeminent clan in the realm, and the most devious schemers in the Empire. Their neighbors, especially the militaristic Sakai, mysterious Itakura, and unorthodox Tatabe, exist in a complicated web of shifting alliances and scandalous plots. The Empire sleeps easier knowing their vast strength has never united since Daikoku's Wager.
ICHIGOKUIchigoku is dominated by a broad river valley and massive wheat fields; it is considered the "breadbasket" of Hachigoku, and home to the some of the most vicious battlefields and interclan grudges ever seen. Four major clans dominate its politics: Abe, Owari, Todo, and Yanisagawa. The Owari are only loosely considered the "high rulers" of the land, with their central position south of the Golden Tears River. Across the river, to the east, are the lands of the Todo, high-spirited rivals to the Owari. The Abe in the northwest strategically manipulate their alliances to keep the two traditional adversaries off-balance, while the Yanigasawa fruitlessly try to stymie warfare from their central position.
Kitagoku (the "North Realm") a vast pine forest fading to tundra in the far north. In addition to the lumber, the realm also relies on the sizeable mineral resources of the Silver Swords and the mercantile wizardry of the independent Yagyu clan. The gruff and imposing Ii guard against threats from the sea, gazing east towards lost Goshima. The Aoyama and Mizuno serve as their most powerful vassals, the first overseeing the mines and the second researching the corrupted Claw Mountains.
Mizugoku (the "Water Realm") holds a labyrinth of valleys, canyons, and even underground rivers slammed between the rolling Green Mountains and the unstable titans of the Cauldron. In ancient times it was a haven for bandits fleeing the law in both the north and south, and small, isolated cultures. After the samurai conquest, the land of lakes also became home to Secret Societies. The strict archers of the Kuroda clan, allied with the magistrates of the Date, fold the foothills of the Green Mountains and guard the high passes into Chugoku. The slopes of the Cauldron are dominated by the Omura, samurai who highly value a monastic lifestyle, and the Tachibana, originators of the two-sword style and champions of the lower castes. Ronin bands and small samurai clans lie between them, and wounds from the past few generations have yet to heal.
Nigoku (the "Second Realm") is divided between the coastal lands considered the cultural heart of Hachigoku, home of the capital Hikari Toshi, and the Lightning Isles ruled by the exiled Yamanouchi. The Shimazu are political masters of the court, supported by their vassals. to the west are the beautiful temples of the Hoshina, and to the east the cliff cities of the Okabe. The southern penninsula is dominated by the wealthy Hachisuka, who vow neutrality and hire out their samurai across Hachigoku.