The Master Sword, too- it wasn't there in the SNES games. Adult timeline-wise, this means it hasn't been found yet. There was once Oracles way to get the Master Sword that had: from the bottom of the ocean.
Therefore, SNES, then the Oracles bring the Master Sword back, explaining why it is there during A Link to the Past.
Even Miyamto always said A Link to the Past is the indirect sequel to The Legend of Zelda and The Advetnure of Link, not the other way round. He made that clear. Storyline has kept it that way, but now other games happen between them.
In the SNES games: no Master Sword, Hyrule hasn't been unified. I read an article, and lots of things about the SNES games point to very early New Hyrule.
Adding to this, Hyrule has a long history during The Minish Cap, meaning the Hyrule has been established for a long, long time. This completely contradicts that The Minish Cap is early New Hyrule, and furthers: other games happened before.
The SNES games seem to set up the early century of New Hyrule, explaining why it actually has a history during The Minish Cap.
Storyline-wise, Twinrova sealed Ganon in the Trident at the end of the Oracles, explaining why he is sealed within the Trident during Four Swords Advetnures. The Ganon in the Oracles is the Ganon from the SNES games trying to come back.
It fits together- Four Swords Advetnures and The Minish Cap mention the Oracles, the Oracles mention the SNES games, the SNES games vaugely reference the flood.
THE BACKSTORY! The Advetnure of Link mentions the time when Hyrule was one country (Wind Waker reference) and Hyrule is in a bad state of needing to be unified. After southern Hyrule is attacked, they move north, the northern land resambles where The Minish Cap takes place, meaing The Minish Cap is set while southern Hyrule from The Legend of Zelda is being rebuilt, in which Four Sword/Advetnures and A Link to the Past, they move back to southern Hyrule.
In The Minish Cap, they're in the norhtern Hyrule that they move to in The Advetnure of Link, and Hyrule appears to have been unified by the events of Four Swords, which is back in southern Hyrule that they left in The Legend of Zelda and were rebuilding during The Minish Cap.
Note: Hyrule isn't unified in The Minish Cap and the first two SNES games. It was unified after The Minish Cap, meaning no non-unified Hyrules can go after The Minish Cap. The Oracles are set after the SNES games.
In Four Swords Advetnures, Ganondorf was sealed within the Trident. At the end of the Oracles, Twinrova sealed Ganon within the Trident. Four Swords Advetnures vaugely references the Oracles, and The Minish Cap even referecnes them.
This places the Oracles before The Minish Cap. They are supposed set after the SNES. In the SNES games, New Hyrule (the supposed new one) hasn't been unified yet, and the backstory vauge reference The Wind Waker directly. In this case, this is early new Hyrule. It is unified after The Minish Cap, which reference the references the Oracles (Four Swords Advetnures references them storyline-wise and makes them come before it), and the Oracles reference the SNES games, which have a vauge and direct connection to The Wind Waker.
After the NES games, the Trifroce is unified for the Oracles to happen right after. After this, the Trifroce is untouched remembered, explaining the unified Trifroce synbols seen in The Minish Cap and onwards.