If you have old stamped passports, send those. If not, do you have boarding passes to the places that you travelled? Submit though as well. I'm not sure what exactly "travel history" means when they deny you as there have been people here that have received that as a reason who have traveled to 76 countries, or who have traveled to 0 countries.... wish there was a solid definition.
Strong ties to country: my bf submitted 2 property papers to the properties that he owned, he submitted my permanent residency card as I live with him in his country, letter from work with information regarding how long he's been there, what he does, salary, and that he has time off. Also explained in a separate letter that he has all his family members here, including 3 children...
We still got denied due to "personal assets" and "ties to home country"

But if you can submit any of those things, I'd do that as well as anything else you own! =)
goodluck!