The history of vampires is rich in both ancient mythology
Despite being one of the oldest and most prevalent creatures of world mythology, the origin of vampires has remained unknown for thousands of years. It wasn't until more recently that we were given a glimpse into the early vampire history.
Only a vampire can create another vampire, so logic tells us that the history of vampires begins with a single vampire who created the others. Much like the chicken-and-the-egg argument, we had little insight into how the first vampire came about until recently. Logically, if there was no vampire to make the first vampire, how was the first vampire made?
According to legend it all began in the Mediterranean.
The first vampire started out as not a vampire at all, but as a human man named Ambrogio. He was an Italian-born adventurer who fate brought to Delphi, in Greece. You can read the full story here, but in a nutshell a series of blessings and curses transformed this young man into history's first vampire.
Specifically, it began with the sun god Apollo (Greek mythology), who in a fit of rage cursed Ambrogio so that his skin would burn should it ever touch sunlight again. Ambrogio's bad luck followed when he ended up gambling away his soul to Hades (Greek mythology), the god of the underworld. The next curse came via Apollo's sister Artemis (Greek mythology), the goddess of the moon and hunting, who made it so that Ambrogio's skin would burn if he touched silver.
The blessings came soon after when Artemis, taking pity on the poor young man, gave him the gift of immortality. He would carry his curses - his skin burning by sunlight or silver, but he would live forever in his current form. Not only that, but Artemis also gave him the speed and strength to become a hunter whose skills were second only to her own.
Blood-sucking (which, by the way, is called "hematophagy" in case you were curious) is also included in this "blessing". In the vampire origin story, Ambrogio hunts swans and uses their blood as ink to write love poems to his lady Selene. While this may be considered a little creepy by our standards, it wasn't all that unusual in ancient Greece to make do with what you hunted.
Ambrogio later moved back to Italy, now as a full-fledged vampire. Legend traces him to the city of Florence (Firenze), where he creates the first Vampire Clan.
We don't know a whole lot about this clan, other than they were most likely willing volunteers - humans who wanted power and immortality, and were willing to trade their souls for it. It was believed that the curse would continue for any vampire where their souls would remain in the Underworld (aka Hades aka Hell), where they could return to claim them, but then could never leave.
From what we know of the history of vampires, the clan grew in size and strength, until infighting created something of a "civil war" within the clan, and many vampires left to form their own clans.
What happened to Ambrogio and those who stayed with him is largely unknown, though many believe that he still resides somewhere in Florence.