One of the best indicators of the Ancient Roman activity you can find is, surprisingly, Greenland's ice.
Since the republican times lead pollution was so strong that it's still detectable now, at over 2800 kms and 2100 years of distance

https://www.dailymail.co.uk/sciencetech/article-5730615/amp/The-rise-fall-Roman-Empire-exposed-lead-pollution-trapped-Greenland-ice-samples.html

#romanhistory #history