By the time our story starts, nothing except the outline of the continents is the same, and in some cases. It is the beginning of an industrial era and most western countries are much more insular than in our timeline. Colonialism has popped up in a few instances, but is not rampant and a slave trade that rivals our Atlantic slave trade does not exist... not yet.
There is immense tension in the Mediterranean between Mithras, Palmyra, and Tengra. The Celti-pact stands with the Palmyrene Empire, while the Nsundi and Tengra Empires stand with Mithras. In book 1, Mithras has taken western Hellas and enslaved its population. In book 2, they take most of the islands in the Mediterranean sea. Instead of acting directly, the rest of Europe and north Africa gather their strength and expect a sign of Mithras mobility to the north, but what happens surprises everyone.
 

Kymbri, Gaelland, and the Celti-pact
Kymbri, Gallia, Eire, Alba, and Gaelland are part of what's called the Celti-pact with Kymbri being the soft leader. Gaelland used to be Germania, but the united tribes of Germania were defeated and now ruled by Gallia and Eire. To add insult, the area was renamed Gaelland and those from the local tribes were treated as second, even third class citizens, though, after about 400 years, it's the rare person who can claim no Gaelic, or Gaulish blood. A majority of the second book takes place in Gaelland as the main characters are put in the middle of class warfare.

Tengra
Tengra is a very large empire stretching from the western black sea to India. They do not typically war with anyone in Europe, but they have spats and short wars with the nomadic tribes of Liao to the north, and especially the Palmyrene Empire to the south. They also have the second largest stake in the Blue Isles.

The Palmyrene Empire
The Palmyrene Empire survives in this timeline and rules a large chunk of the mediterranean and the Nile. They have a good relationship with the members of the Celti-pact, but extremely poor relations with Tengra and Mithras. It is so bad that trading in the mediterranean feels like being put into a boiling pot.

Ambitions of Mithras
Mithras is a sleeping bull ready to buck and skewer everything around them. When Rome fell, Aurelius never got the chance to put it back together. The Mithran cult became militant and turned the empire into a theocracy. They consolidated their power and relinquished control of many territories. For hundreds of years they kept relatively quiet until recently. They fought a silent war with Kymbri and Palmyrene over the Blue Isles and won with the backing of Tengra and the Nsundi Empire. Afterwards, all three started exploiting the area and enslaving the inhabitants. In the first book, Mithras annexes and enslaves most of western Hellas. In the second book they take multiple islands in the mediterranean. This leads to the first Mithran war in the third book.

Vinland in Hanuah
When the Northmen came to Hanuah, they created Vinland and it was not abandoned like in our timeline. Instead, they made a pact with the natives. European diseases hit the natives much sooner, but at the time, no foreign power was able to take advantage of it. With no notion of conversion, or manifest destiny, few even cared. Over time, this allowed the natives to regain their numbers. The Norse cultures in Vinland eventually blended with the natives, creating something unique.

Brigantia & The Haudenosaunee
When Kymbri went to establish trade with Hanuah, they decided to cut out Vinland as a middleman and contacted the Haudenosaunee Confederacy who were 10 tribes strong. After a Druidi did them a few good turns, they allowed Kymbri to establish a trading town. Many years later, there are more trading towns and the area is known as Brigantia, named after the Kymbrian's chief Goddess. There is much intermingling of the two cultures and there are some on both sides who disapprove of this.

The hopes of the Nsundi
The Nsundi Empire is the most powerful force in western Africa. Most of their wealth comes from sugarcane in the Guianas and domestic rice through slave labor. The Mali Empire and Zigharan's are understandably weary of their advance north. The Celti-pact consider the Nsundi as a potential treat because they backed Mithras during the silent war in the Blue Isles