There are a lot of parallels with Yelm. Shargash is both a celestial and underworld deity. He is associated with Death. But where Yelm is a Restorer, Shargash is a destroyer. He purifies things by destroying them, and then placing the ashes within his Enclosure. In Dawn Age Alkoth, Shargash initially eclipsed Yelm, but with the return of the Dara Happan emperors and Yelm Imperator, the Shargash cult returned his father’s accoutrements and powers.
There are a lot of parallels with Storm Bull and Zorak Zoran as well. One God Learner theory is that every element had its disorderly destruction god – some even experimented with the idea that Shargash is the celestial aspect of Zorak Zoran. Those experiments failed and the trolls utterly reject the comparison. The Shargash cult’s hatred of trolls does not help would be investigators.
However, the identification with Shargash and Tolat was easily confirmed and nobody doubts the confirmation. Tolat and Annilla are often associated with each other, and this connection is of interest to the Lunars. Again, the enmity between the Shargash cult and the trolls makes working with the Blue Moon troll impractical. There are some Lunar scholars that think the Blue Moon worshiping humans of Pamaltela might be more useful, as they worship both Annila and Shargash!
The Orlanthi have little use for Shargash, likely because of the surfeit of Death and Disorder gods already in their pantheon – Gagarth and Storm Bull are enough for any pantheon! The Orlanthi claim that Orlanth defeated Shargash in the Gods War – avenging his father’s destruction – and cast him down into the Underworld.
Shargash and Yelmalio dislike each other, and most claim that Yelmalio defeated Shargash after the Greater Darkness, as Shargash would not stop his destruction even after the Gods War had ended.
So Shargash is the manifestation of the red planet – which is universally associated with war, aggression, and death. It is pretty easy to analogise him to the Mars or Mangala.
In the Dawn Age, the Alkothi went a little nuts with their claims of his cosmic importance. Those claims receded greatly when Khordavu became the first true emperor. And then they got the teeth kicked out of them by the EWF, Red Emperor, and Sheng Seleris. In the modern era, I can imagine some Lunar poets treating Shargash with some amount of ridicule like Homer does Ares. In Glamour, Shargash might even be a popular Alazon or il Capitan figure.