Here is a rough draft for a timeline of the Tanagoro humans of Mystara. The sources I have used are mainly the HW boxed Set, DotE and CoM, as well as Daniel Boese's Mystara Timeline. Let me know if I have missed anything!
Tanagoro Timeline
by Håvard6000 BC
There is no true civilization in the Outer World. Humans are tribal hunter-gatherers, living mostly in plains and light forests. They are divided into three great races: Neathar (light-skinned), Oltec (copper-skinned), and Tanagoro (black-skinned).
4000 BC
The Blackmoor Civlization begins its rise. On the eastern part of the Northern Continent, Neathar humans of The Thonia Empire make contact with Tanagoro to the south, whom they call “Bolgers”.
3000 BC
The Great Rain of Fire
Two races of humans come to the land that will later be called the Minaean Coast. From the east comes Tangor Man, driven from his home by climatic changes brought on by the Great Rain of Fire. From across the waters to the west comes Oltec Man on one of his great colonising migrations.
Some Tanagoro are brought to the Hollow World by Ka and Korotiku. The Tanagoro are placed in the plains south of the great equatorial mountain range, south and west of the Brute-Men; the Tanagoro think of those races as monsters and keep well away from their hills and mountains.
2500 BC
Tanagoro colony on Zyxl
2200 BC
Some Tanagoro colonists from halfway around the world reach the Serpent Peninsula and decide they like the abundant rain forests. However, the elves regard their slash-and-burn agriculture with horror. Eventually, they work out a compromise: the Tanagoros keep to the coastlines and forest fringes, while the elves withdraw deeper into the forest.
2000 BC
Tanagoro arrive in Izonda, on Davania.
1750 BC
The earthquakes that rock the Sea of Dread drastically change the Serpent Peninsula. Unknown to all, an artifact of time hidden beneath the sea is uncovered. It begins influencing the minds of the people living in the region. The Tanagoro culture on the Serpent Peninsula collapses into warring tribes. Some carve out land for themselves on the Thanegia Island.
1600 BC
Southbond Tanagoro expedition launched from Skothar. It will eventually reach Vulcania.
1500 BC
Westbound Tanagoro expedition launched from Skothar. It will eventually reach the Pearl Islands.
Tanagoro on the Serpent Peninsula are weary after a century of warfare. They begin to come to peace with the Sheyallia Elves of the region. Tanagoro Humans and Elves live side by side. Both elf and Tanagoro children begin being born with precognitive abilities.
1200
Tanagoro Colony established on Vulcania by colonists from Skothar.
1000 BC
Tanagoro explorers from Skothar settle in the Pearl Islands befriending the Sprites who live on the Islands. The Tanagoro call the largest island of the chain Nu-Ar; “Western Home”. Eventually they encounter the Alphatians who incorporate the Pearl Islands into their Empire.
556 BC
On the Serpent Peninsula, Yav is born to a Tanagoro Human and Elf parents.
529 BC
On the Serpent Peninsula, revolts take place against the ruling class of Seers. The situation spins out of control resulting in civil war pitting Tanagoro and elves against each other. Yav disappears. Legends of Yav as an Immortal begin to spread.
500 BC
Under the identity of Mulogo, Yav leads the Serpent Peninsula Tanagoro on a mass voyage to the Immortal’s Arm.
480 BC
Yav returns to Thanegia and discovers the artifact of Time which has had such a negative influence on his people.
400 BC
Yav realizes that the artifact he discovered in 480 BC has sent him into the future. He returns to the Arm of the Immortal where his grandson ruled over five allied city states. He persuades his grandson to organize a mass migration back to Thanegioth Island where he issues the Precepts of Yav. He then uses the Artifact to travel to the year 1 AC
0 AC
Hoping to be liberated from Alphatian domination, the Pearl Islands side with Thyatis. However, the Thyatian Emperor Zendrolion I secretly kills the Nuari King along with other rivals.
1AC
Realizing that he cannot travel back in time, Yav seeks to find a way to remove the destructive effects of the Artifact. He makes many dangerous journeys to repair the artifact. In the end the artifact sends him to the year 750 AC
20 AC
Due to the machinations of Empress Valentia of Thyatis, the Pearl Islands become fully incorporated into the Thyatian Empire with Pearl Islanders as full citizens.
750 AC
The various tribes of Yav now speak a number of different languages and have distinctly different cultures. Yav reappears with his artifact. He eventually finds one of his descendants and helps him lead the People of Yav to a new way of life.
758 AC
Yav ascends to Immortality. The Most Serene Divinarchy of Yavdlom grows into a thriving united civilization ruled by Seers and Prophets.
1000 AC
The Present.