I was reading a post that talked about likely trade between the Japanese and basic American cultures, it made me curious what they wrote about the people's and if they ever tried to conquer any territory.
Not that we know of.
We know families and bands kept local contact across the Bering Strait, but we're not sure how far contact stretched.
In the past 30 years, archaeological digs have uncovered a handful of Asian artifacts that can't be explained except by long-range exchanges. Here's the story of a 1,000-year-old cast bronze buckle found in northwest Alaska. I also had the privilege in 2013 of personally examining a brilliant blue bead found in a pre-Russian archaeological dig in Kodiak. I spoke with the archaeologist conducting the dig, and he said that until the bead is examined by an expert, we can't say if it's Russian or not. It was found at a level consistent with the pre-Russian period. I don't know if it was tested or not
The thing is, we know long voyages are possible. Alutiiqs from Kodiak traveled down the Aleutians before Russian contact, and in the late 19th century, a kayak was paddled from Kodiak to San Francisco, we believe.
Even today, adventurers paddle the Inside Passage. In 2013, a Minnesota gentleman traveled 5,000 miles in 5 months, going from Seattle to Skagway, over the Chilkoot Trail, down the Yukon River, across Bristol Bay, up to Lake Iliamna, across Cook Inlet, ending in Anchorage.
We also have evidence of regular trade routes between Kodiak and southeast Alaska. Now, we know it was possible to head west instead of east -- but would it be worthwhile to do so? Does that cast bronze buckle indicate occasional, hand-by-hand passage of artifacts, or does it indicate an established trade route?
That, we do not know.
We do, however, know definitively that Japan did not attempt to conquer any territory in North America until 1942. There is no archaeological, cultural or social evidence of this in either Alaska or Japan. There is also no definitive evidence of direct Chinese visits to Alaska, and China was by far the stronger nation until the latter 19th century.
Heck, there's not even definitive Japanese cartography of Alaska before the Russian expeditions of the 18th century popularized the northwest coast of North America. As late as 1802, there were not even definitive maps showing Sakhalin Island. Kondo Morisge's Ezochi Zushiki is vague on the whole thing, and it's one of the more famous maps of northern Japan in that period.
Here's a nice overview of Japanese cartography by Kazutaka Unno.