DA1 "Adventures in Blackmoor" provides a great deal of background, although doesn't cover the setting's earliest years, and lacks any dates.
Fortunately, D.H. Boggs has compiled an invaluable chronologic resource (see "A Blackmoor Timeline") which can be used as a handy reference guide.
Below, I've extracted and lightly edited a timeline of the more notable events, for those wishing to run "Adventures in Blackmoor".
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995: The Northern Marches are invaded by the Egg of Coot. Blackmoor town is burned and the castle is heavily damaged. The Egg of Coot's forces are ultimately defeated, and Fant of Bramwald is granted the Barony of Blackmoor.
996: The Great Svenny, Bishop Carr, Willem of the Heath, and Mello the Halfling build Svenson's Freehold to guard Wolf's Head Pass "some five miles to the northeast of the Castle along the only road that leads to the southern confines of the Egg of Coot".
997: The Second Coot Invasion. Svenson's Freehold is destroyed. Blackmoor Castle is attacked and conquered by the Grand Army of King Funk I of the Orcs of the Black Hand. Elven armies eventually drive back Funk's orcs and retake the castle.
998: The Third Coot Invasion. Orcs of the Black Hand under King Funk I with their monstrous allies emerge in mass from Blackmoor dungeon and join the Egg of Coot's offensive. The Empire sends reinforcements.
999: King Funk I is driven back into Blackmoor dungeon, retreating to the 10th level, and elven armies retake control of Blackmoor Castle. The last of the Egg of Coot's forces are defeated, and victory is declared. The Regency Council is established.
1000: Toska Rusa, the Afridhi high priestess, receives a grand vision of conquest from Zugzul. The god promises her a great empire for her people and she promises to build him a temple made entirely of gold in the heart of the Empire.
1003: The Afridhi invade the Plains of Hak.
1004: The Afridhi reach the Duchy of Ten and threaten her border.
Uther at the Berne
1005: Uther Andahar's father is killed in a Skandaharian raid. Uther becomes the new Baron of Blackmoor. The forces of Ten attack Blackmoor but are broken and beaten at the Battle of Lake Bern, due in large part to a brilliant heavy cavalry charge led by the young baron.
1006: The Afridhi attack the Duchy of Ten. The campaign bogs down into a series of sieges.
1007: Restoration of Blackmoor Castle as a residence. The Regency Council realizes that the Duchy of Ten will soon fall to the invading Afridhi. It sends a petition to the Emperor asking for permission to send an army in relief of their former enemies in Ten. Their petition is scorned.
1008: The Fourth Coot Invasion. The Egg of Coot launches what it hopes will be a swift surprise attack. Uther Andahar, assembling an army for a strike against the Afridhi, marches his army to intercept the foe. The Egg of Coot's forces are caught and driven back.
1009: Events of "Garbage Pits of Despair" published in Different Worlds #42 (May/June, 1986); #43 (July/August, 1986)
1012: The Duchy of the Peaks allies with the Afridhi, who are completing their conquest of the Duchy of Ten.
1013: Uther’s efforts to clear Blackmoor dungeon suffer a setback as undead overrun the guards stationed on level 2. The baron orders the dungeon sealed. The Duchy of Ten is struck by a devastating plague, temporarily slowing the Afridhi plans for conquest.
1014: The Afridhi probe Blackmoor's defenses through an attack against Han Aleford's Barony of the Lakes. The Afridhi are repulsed but Aleford is accused by the Emperor of having compromised a possible truce. The Emperor sends the Imperial Governor of the North to arrest Han Aleford, but he is stopped and sent back by Uther, who considers Aleford a friend. The Emperor is incensed and sends an army to teach Uther a lesson.
Uther and the Thin Black Line
1015: The imperial army occupies Blackmoor Castle after Uther withdraws to spare the town, takes shelter with the dwarves under the leadership of Urberstar Kazakhum and secretly builds up his forces. Uther routs an imperial force at the Battle of Root River, reoccupies Blackmoor Castle, and is recognized as King of Blackmoor by the Regency Council. Uther is victorious at the Battle of the Neck. 10,000 Afridhi are slain, losing an entire wing on the banks of Lake Temperance. Han Aleford is killed. His daughter Rissa Aleford becomes the new Baroness of the Lakes.
1016: Skandaharian forces raiding Blackmoor under Jarl Thorsen One Thumb are defeated at the Battle of the Downs.
1018: Uther intercepts an army sent by the Empire in the Crystal Peaks and defeats them soundly.
1019: The Great Svenny is promoted to baron; founds house Zvenzen and builds Newgate. Svenson takes control of Williamsfort and rules from Newgate. A sharp drop in land values causes Willem of the Heath and Mello heavy losses, ending their rival cartel. Nicholson’s Merchant Mafia buy them out and form the united Northern Guild of Merchants.
1020: The Eldritch Underground launches a surprise attack on the Wizard's Cabal headquarters at Vestfold, killing many of the wizards present. After a two day battle, the Cabal emerges victorious. The uprisings leader, Tamis Azkanikin ("The Green Mage") escapes and goes into hiding.
1021: The Fetch leads an expedition to the City of the Gods, but only a third of the party survive.
1023: Bascom Ungolian, the Baron of Glendower, leads an expedition into the lands of the Egg of Coot to free his kidnapped wife. The expedition is ambushed and Bascom's fate is uncertain.
1024: The Sixth Dwarf-Orc war. Uberstar Khazakhum, Regent of the Mines, is captured by Orcs of the Black Hand in the Crystal Peaks. Lortz Kharnandrhum, the son of Uberstar, becomes interim Regent of the Mines. Lord Lortz invades the orc stronghold in a failed rescue attempt. The dwarves are pushed back to the gates of their own Northern Delving, where they are besieged by the orcs, cutting off communications with Blackmoor. The war spreads to the Stormkiller Mountains by winter.
1025: Events of DA1 "Adventures in Blackmoor"