I have said time and time again, but you keep missing them! There was a theme of unflooding land and decreasing water levels in Phantom Hourglass for the future; in Oracles of Ages, when you travel to the past, there is more water and more land in the futre, and it almost mimics the event involving land and water in Phantom Hourglass.

Not just this, but in the very same place involving water in the past and land in the future (the commonly unnoticed connection to the past and present of Oracles of Ages), but the boss enemy of that very same area involving water and land is strong and his name is... Eox.

Cobble have the theme of water and land from Oracles of Ages, and a boss character there connected to them is strong and his name is Eox. The Cobble are connected to a character who most definately is Gerudo.

So, Cobble seems to have some form of connection to a Gerudo character, and they are connected to a character called Eox, and both the race and boss is similar to Onox from the Oracles. Onox is connected to the Gerudo and Eox, and Eox from Phanto0m Hourglass himself is connected to a race that seem to have something to do with the Gerudo.

It's hard to explain, but there seem to be more connections than that, but in summary:

Cobble have Eox, and they have something to do with the Zuna and Gerudo, who both dwell in the same desert during Four Swords Advetnures. In Oracles of Ages, there is Onox, very similar in both name and something about them both to Eox, and both seem to be connected to the Gerudo. Onox is also conneced to Veran, who dones the Gerudo synbol and seems to be connected to the Zuna/Twili, who are connected to Gerudo and seem to be connected to Cobble from Phantom Hourglass, who in turn are connected to a Gerudo character in that game!

Looking at everything, Phantom Hourglass made strong ties to Four Swords Adventures (Force Gems, Cobble/Zuna, the Four Royal Knights, the possible survivial of Gerudo) and the Oracles (Eox/Onox connection, Cobble's connection to Gerudo and Zuna/Twili being similar to Onox's and Veran's connection to Gerudo and Zuna/Twili).

Four Swords Adventures and the Oracles always had some form of vauge connection if you looked deep enough, and the Phantom Hourglass seems to connect to them both with its two very likely Gerudo characters (Astrid and Zauz), and how those two characaters are connected to Cobble, who have Eox and appear to be connected to Zuna, who are also connected to Gerudo.

Astrid is clearly Gerudo, but I don't know if you're played Phantom Hourglass. Zauz looks exactly like (skinny) Ganondorf, and he has knowledge of the Trifroce, despite the flood events. Both Astrid and Zauz, who one appears a Gerudo woman and the other looks (quite frightenignly) like Ganondorf, both clearly say they're connected to the Cobble, and both are Gerudo-appearing characters. Cobble themselves are connected to the desert and seem to be connected to Zuna, who are connected to Gerudo. They have Eox, who seems to be connected to Onox, who is connected to the Gerudo!

Put all all together, and the you can clearly see the whole connection between thew games, and the creators put them there as sort of... 'psuedo-secrets' and strong timeline indicators because Phantom Hourglass makes connection to Four Swords/Advetnures and Oracles of Ages, and it even makes connection to The Advetnure of Link, which the Oracles overworld appears to be part of.

The Adventure of Link map itself appears tio have the Four Swords/Adventures overworld (southern Hyrule), Holdrum, Labrynna, The Minish Cap's Hyrule, AND World of the Ocean King (unflooded).

You might have noticed the obvious connection between Phantom Hourglass and The Advetnure of Link, for a start. The Adventure of Link appears to contain Holdrum, Labrynna, The Minish Cap's Hyrule, and World of the Ocean King, Adding to this, Phantom Hourglass also makes reference to all of the games that those lands appear in.

I think the connection between Phantom Hourglass and The Advetnure of Link together is a huge timeline indicator, because Phantom Hourglass seems to forehadow, reference and connect to most of the 2d games, then The Adventure of Link, set after, has their overworlds.