They are thought to be the ancestors of the people of Prox, as Proxians refer to themselves as members of the "Fire Clan of the North". This is made more credible by their settlement's close proximity to Mars Lighthouse. Once guardians of the lighthouse, they seek to reignite the beacon after their current leader, Puelle, discovers that the growing rift to the north is the result of alchemy's absence in Weyard. This is the cause of nearly all events in the entire Golden Sun series, as Saturos and Menardi are sent to the village of Vale to pilfer the elemental stars, and so forth. The present-day Mars Clan members, (assuming the Proxians are in fact descendants of the clan) have developed scaly bodies to adapt to the cold, and have various skin colors, ranging from pink to blue to green. Thus, they appear to be closely associated with dragons; this happens to be the symbol for Mars, as seen in Mars Lighthouse.
Connection with Mars Lighthouse
This association with dragons is also clearly shown in both Golden Sun games. In the first installment, Saturos and Menardi meld together upon the activation of the Venus Lighthouse into the Fusion Dragon; a huge, two-headed beast overflowing with Psynergy. In The Lost Age, the replacements of the slain duo, Karst and Agatio, are transformed into Flame Dragons by the Wise One after succumbing to Mars Lighthouse. Agatio also employs his exclusive Psynergy Rising Dragon during both battles in which he is fought.
This opens up the possibility that all of the Elemental Clans underwent some sort of mutation corresponding to the symbolic form of life they were associated with, during their prominence in Weyard's ancient past. This can be somewhat seen with several of the surviving Mercury Clan members, such as Mia, Alex, and Rief, as they all have strikingly blue hair. Also, the Anemos, of which Hama and Ivan are descendants, are generally accepted to be the ancestors of the people of Contigo and Shaman Village, and are said to have possessed the ability to fly.
The dwarf race of Loho apparently migrated from the Northern Reaches to their current settlement in search of mining grounds. Because they do not appear to demonstrate any Psynergy, however, it is much less plausible that they are direct descendants of the Clan.