"Earl Tilgar reclaimed the town and destroyed the few demonic forces that had survived Assur's death. In the following years, after weathering a devastating famine that cost many lives, he founded the dynasty that ruled Entsteig until the capture and binding of the Prime Evils themselves, some six hundred years later" (pg 67-68). Two years after Bartuc's death.
This story expands to over a year. Kabraxis is unleashed at some point at the beginning of the book, and over a year later (at the end of the book) is defeated. Towards the end of that year's gap it is stated that Tristram was recently destroyed by Diablo. It is also stated by Deckard Cain that Tristram was corrupted for nearly four years. So Tristram fell before Kabraxis was released, but the actual Diablo game where Tristram is apparently saved happens in the middle of this novel, before Kabraxis is defeated.
"It has been more than a year" (pg 147) (Referring to the events at the beginning of the novel)
"Diablo returned to this world only a short time ago by corrupting the Soulstone that bound him." (pg 148) (Said at the end of the novel)
"Ogden has owned and run the Rising Sun Inn and Tavern for almost four years now. He purchased it just a few short months before everything here went to hell." (Deckard Cain, Diablo I)
"Night fell upon the desert of Aranoch ... And from beneath the sand slowly emerged a monstrous form ... Xazax rose unsteadily... And before the hellish mantis loomed the most terrible of all the nightmares he could have dreamed. The demon’s mandibles stretched wide and a single, almost plaintively spoken word tried unsuccessfully to completely escape."Diab—"" (Epilogue)
Before the Moon of the Spider but no mention of the Worldstone, so it is assumed that this book also takes place before it is destroyed (see Moon of the Spider section for quote). Zayl traveled from Ureh to Westmarch and would have likely to have had to pass through the Rogue Monastary (apparently the only path to Westmarch if traveling through the twin seas, which Zayl very likely would have). With Andariel and many other demons out and about during DII, and no mention of a hazardous journey to Westmarch, it is unlikely that he was traveling during the events of Diablo II, but was actually in Ureh at the time. Its more likely that Zayl left Ureh to travel to Westmarch after Diablo II, which means that The Kingdom of Shadow must have happened parallel to Diablo II and the destruction of the Worldstone.
"I believe, as you do, that this may very well have been Diablo himself!” (pg 179)
“For now you are one of the few fortunate ever to cast your eyes upon one of the wonders of the past—fabulous, lost Ureh!” (pg 9).
"In truth, [Zayl] could actually not be certain that the Worldstone had been destroyed, but the evidence was certainly there. Mount Arreat - where legend claimed it had been hidden - had exploded, its entired top ravaged. The destruction had been heard about even here in the far-away Westmarch. More to the point, the rumors among those with the sight gave starker credence to the horrific claim. It was said that one of the Prime Evils themselves - Baal, Lord of Destruction - had been the cause, and if so, the mortal plane was in for far worse to come. The Worldstone had existed since time immemorial, created, so the teachings of Rathma said, to keep the mortal world protected. Now, both the powers of Light and Darkness reached out to fully claim humanity, and in their battles against one another the two cosmic factions threatened to destroy what they desired. Somehow, all that tied into Zayl's own urge to come to Westmarch. Somewhere in this vast kingdom, the repercussions of Baal's heinous deed would soon be felt."(pg 19)
"'Twas cursed ones who took Zayl's hand, slavering damned souls from a lost city called Ureh" (pg 81).