Yeah I couldn't fine much online apart from some folks asking the same questions you are about the brand as well as a few ads. The thumb shifters and front wheel are replacements. My guess is that those are Exage Trail components? ~1988 Comparable to a Specialized Hardrock, so nothing to get that excited over. It might be hard to locate something else in this huge size though.
Your best bet to find out more is to hope T-Mar sees this.