The Aquiliad3 books in series
Aquila in the New World Publisher's Summary
On this alternate Earth, Rome rules all...including the New World, known in other dimensions as America but here as Terra Novo.
General Titus Papinianus is governor of that untamed land, and Aquila, chief of the savage Lacoti nation, is a Roman senator. But official titles aside, their duty is to Caesar. So when Caesar sends them on a quest for the fabled land of China, thought to be somewhere in Terra Novo, off they go.
They are hardly prepared for bloodthirsty Aztecs, flying machines, time-traveling aliens, or Bigfoot - and Aquila’s problem-solving strategies are unconventional to say the least!
Before they know it, their adventures lead them into the hands of the Time Criminal, who is bent on altering all the multiple universes to suit his own evil whims. Somehow they have to stop him...before their world is destroyed!