Just how much has been changed though?

The origins of Guns and Gunpowder are highly questionable as there is documentation of The Devil bringing the idea from another plane, originally calling it Devil's Powder in 1313

Just as well, in the year 1666 the start of the Annual State Owners National Casino hosted in Virginia, there exists multiple timelines due to one Blackledge family acquiring all of Virginia and gambling against every state owner of the united states in attempts to take over the Country as Isaac Newtons idea of the Fluxion in that year, led to the creation of the matrix and a period of shared consciouness until his death.

That is the point up to where shared consciousness allows the future to alter the past. But for actual time travel brought on by visiting a vibrationless world, while time is a vibration, allowing a person to visit every moment of it simultaneously.

-UMBRA

Though it may not seem as a reasonable thing to do advancing weaponry a couple hundred years earlier, it is more responsible to have bullets in case of trouble than it is to not have bullets and be surrounded by trained swordsmen.

The biggest risk factor of the change appears to be the increased death rate causing some peoples complete disappearances upon entering the new timeline due to their ancestors having died earlier.

They can still be contacted however using Interferrometry to observe reflections of lasers through smoke to figure out which theoretical ruleset rules the given space, and then proxy through each location to interconnect dimensions. The same rulesets have been used to put alternate galaxies into the same timeline as one another, effectively changing the paths of everything within them as they enter a Entangled state.

These rulesets are important for control states used during the STAR game, as the entanglement of a galaxy to a person or space allows possession to occur.

-UMBRA