[Lasombra] is the name "modern" Cainites use (the term dates back to the Roman Empire). Around 1991 BCE, [Lasombra] was named Lau-Som-Bheu, which can be translated from Proto-Indo-European as "profiting by knowledge" or "profiting together through domination". His priests among the seafaring people worshipped him as Laza Omri Baras, the "God of the River of Darkness".
|“||Who was Lasombra in life? Perhaps he was himself a man of power. I suspect, however, that he was a pathetic failure, Embraced (as we call it) for some trivial reason, who flourished unexpectedly. Someone who had lived with real success would surely not be so obsessed with the matter forever after. Gratiano was perhaps what Lasombra wished he had been.||”|
|— Ming, Clanbook: Lasombra Revised|
After the fall of the Second City, [Lasombra] returned to the sea, eventually settling on an island in the Mediterranean (which one is not certain, the most likely being Malta). From there, he assumed command over the pirate people of the Hyksos, directing them against the civilizations populated by his brothers' progeny. Still, [Lasombra] himself was seen little in those days. He dwelled upon an island, some said, or in the depths of the wine-dark sea, rising from time to time to hunt and to guide his worshippers. Occasionally he granted his Embrace to a chosen few, but this happened less and less often as time passed. For centuries, the Sea Peoples were strong under the watchful guidance of their dark god. After the eruption of Thera, darkness clouded the sky and [Lasombra] left the sea, wandering extensively across the earth, visiting strange cultures and engaging in social experiments to search for desirable childer, as evidenced in Montano's Embrace around 1496 BCE.
When [Lasombra] returned in the early age of the Roman Republic, he took residence in Sicily, building himself the tomb-fortress that would be called the Castle of Shadows by his descendants. There he would remain, in torpid meditation, attended only by his closest childer, contemplating the great Abyss. Occasionally, he would awaken and leave without announcement. This made him one of the more active Antediluvians of the time, as the only other directly active Antediluvian was Tremere, in the short period of time before Saulot's consciousness overwhelmed him. The Sea of Shadows, one of the great Kindred feudal realms of the age, was nominally under his control, but he delegated much of the administration to his childe Montano. In his waking time, however, [Lasombra] took a keen interest in the developments of the world, searching for more potential childer.
The Sabbat scholars claim that [Lasombra] sealed his fate when he introduced the young Italian bishop Gratiano de Veronese into the Clan, ignoring warnings from Montano. Among the Lasombra, there is still debate about the motives of [Lasombra] to introduce Gratiano into the Clan. Some believe it was a plan that had gone awry, others that [Lasombra] finally felt the weight of ages and wanted to commit suicide, others that his mind had become feeble and weak, and others even presume the influence of infernalists and other forces behind it. Most believe that it does not matter.
|“||None of you know what it's like to exist in the presence of a god, or something so powerful that it might as well be a god. You look at your leaders in the Festival and find them intimidating, but not one of them is more than four centuries old. I was the oldest present at the rite, and I am less than a thousand years old myself. But I know what our founder's gaze was like, and why it made the great patricide necessary.||”|
|— Brother Oso, Clanbook: Lasombra Revised|
There is another tale, fiercely denied by the Sabbat. It tells that [Lasombra] allowed for his own diablerization, to free himself from the shackles of his physical body. After that, his soul entered the Abyss, seeking to become one with it. In the process, he became more than a mere vampire, turning into an abyssal monstrosity void of any remains of humanity that were left in his undead form. Unfortunately for [Lasombra], the native beings of the Abyss regarded the creature as insignificant for his past as a creature of flesh and it seeks to remedy this by causing the Abyss to collapse into the physical world, blotting the sun out forever and recreating the original world, before God created light. To this end, it has begun to use those who command Obtenebration as his sensory organs in the physical world to find a way to achieve this goal.
|“||As we were scouting the place out, we found Him. Him. I don’t know if He was our clan founder, just a real old Keeper, or something completely different, but when He saw us, we felt the pull to his gigantic mouth, his all-consuming black hole. The void was calling. I wasn’t the only one to see Him out there... Some claim to have encountered Him in Libya, others in Afghanistan. There’s even a report of His presence in Sicily, and some claim the so-called Emperor of D.C. is just Him in another form.||”|
- Abyss Mystics have discovered over four hundred names for the Lasombra Clan founder, and these names still have a potent sway over the denizens of the Abyss, for example - "Lau-Som-Bheu," which is quite passable Proto-Indo-European for "profiting together by knowledge" or "profiting together by domination". 
- The Ventrue have referred to Lasombra the Antediluvian as Lucien, "who drove his brother into torpor and salted the earth where he lay."