Marriages between kingdoms under the Targaryens?

[The Merling King]

Prior to the Southron Ambitition and Aegon V, how common was marriages between kingdoms? I read that Tya Lannister wed Gowen Baratheon during the time of The Hedge Knight but Gowen was most likely not the lord or heir but a younger son. Any other examples? The Angevin Empire is a historical example were Norman Dukes ”lords paramounts”(and kings of England) gained control of more French territory then the King of France through marriage and maternal inheritance like Anjou, Aquitaine and Brittany. I am curious if a marriage between a LP male heir and daughter of LP could take place without the approval of the royal family. Like Robert and Cersei or Renly and Margery if the they were not the new royal family. The Targaryens would probably be less concerned about a marriage between a Stark and Tully than the southern kingdoms but they’re power had already been weakened between the WO9PK and RR. Any thoughts?

[Lord Varys]

Rhaenys and Visenya and Alysanne also organized many marriages between the kingdoms, both involving great houses as well as not so great houses.

For the Starks we can say that they were very insular in their marriages, focusing mainly on their own bannermen in the 2nd and 3rd centuries (the rare exceptions seem to be love matches in exceptional circumstances - like Cregan and Aly - and second marriages - like Melantha Blackwood).

For the Lannisters we have less data, so but there is also a tendency there to marry among Westermen and their own family (Tywin and Joanna aren't the only Lannisters marrying each other).

But in general I'd expect there to be more intermarriage between the southern kingdoms, especially in the border regions, especially with the Riverlands, Westerlands, Reach, Stormlands, and Crownlands.

The Vale might also be somewhat insular considering they are very self-contained.

The concentration of lordships like they are now happening with Tommen (who is heir to Casterly Rock and Lord of Storm's End and Lord of Dragonstone in addition to being king) were prevented earlier, presumably by royal decree preventing double heirs from claiming more than one lordship.

And one look in the present state of affairs as well as the history of Westeros shows that marriages don't mean (lasting) alliances. Genna-Emmon didn't establish a bond between the Twins and Casterly Rock, no marriage could bring the Brackens and Blackwoods together, the Lannisters literally destroyed the Baratheons after Cersei married Robert, etc. In that sense one can expect there to be a number of signficant marriages throughout the kingdoms which eventually led nowhere.

[The Merling King]

1 hour ago, Lord Varys said:

The concentration of lordships like they are now happening with Tommen (who is heir to Casterly Rock and Lord of Storm's End and Lord of Dragonstone in addition to being king) were prevented earlier, presumably by royal decree preventing double heirs from claiming more than one lordship.

It seems very unlikely for dual lordships as male lines last for thousands of years and also the importance of family names to GRRM. If a Renly Baratheon-Margery Tyrell type marriage took place under the dragonless Targaryens it would probably cause a lot of concern.

1 hour ago, Lord Varys said:

The Vale might also be somewhat insular considering they are very self-contained.

Both Janes Arryn and Rhea Royce lands and titles were inherited by a relation within there internal family. 
 

Does anyone know what happened to Rowena Webber’s land after she married Gerold Lannister? Also I wonder if when the male Lannister line ran out and the king of the Rock wed his daughter to an Andal in exchange for him taking the Lannister name would it have been a good time for say a Gardener king to try and present his son as a worthy successor and unify the 2 kingdoms?

[Lord Varys]

24 minutes ago, The Merling King said:

It seems very unlikely for dual lordships as male lines last for thousands of years and also the importance of family names to GRRM. If a Renly Baratheon-Margery Tyrell type marriage took place under the dragonless Targaryens it would probably cause a lot of concern.

Margaery wasn't an heir. There shouldn't be an issue with such a marriage.

There are cases where lines were usurped and pushed aside by way of marriage (like how the Graftons did it with the Shetts, back during the Andal conquest) and we can also expect there to be many a house being taken over by one of the greater ones as the Hundred Kingdoms became the Seven Kingdoms by means of marriage.

The completely unrealistic part of George's world is that house/family names would be important (and perhaps there aren't all that important but rather appear this way due to the fact that lords and ladies are styled 'Lord Baratheon' or 'Lady Stark') and that there wouldn't be many noble houses making a Hapsburg-like career - rising from obscurity to imperial dominance by means of a number of very advantageous marriages over the decades and centuries.

But that's kind of an unrealistic underpinning of George's world-building. It is where his noble framework has literally nothing to do with real world feudal settings.

24 minutes ago, The Merling King said:

Both Janes Arryn and Rhea Royce lands and titles were inherited by a relation within there internal family.

Sure, my idea was that the Vale is a place with natural borders possibly indicating that the people there do not important brides from elsewhere on a regular basis.

But then - the best indication for the 'normal marriage habits' of the southron nobility should be reflected by the Frey appendix. Walder and his descendants have spouses from all over Westeros - from the Riverlands, the West, the Reach, the Vale, the Stormlands, and the Crownlands.

Thus we can expect that a house with the power and wealth of the Freys from the southron kingdoms would intermarry with a similar number of houses from all over Westeros. The North and Dorne would feature less prominently because they are backwater/peripheral regions one would not feel a great need to be close to.

24 minutes ago, The Merling King said:

Does anyone know what happened to Rowena Webber’s land after she married Gerold Lannister? Also I wonder if when the male Lannister line ran out and the king of the Rock wed his daughter to an Andal in exchange for him taking the Lannister name would it have been a good time for say a Gardener king to try and present his son as a worthy successor and unify the 2 kingdoms?

No, we don't. There is a Webber with the Windblown in ADwD who supposedly lost some lands in Westeros. If this is a descendant of Lady Rohanne then one could assume that Ser Eustace and Lady Rohanne did produce a son or a couple of children before Eustace died and Rohanne was free to marry a widowed Gerold Lannister - one assumes she only considered doing that after Gerold had become Lord of Casterly Rock.

If she dumped her child to rule Coldmoat and it got infected by Eustace's Blackfyre shenanigans (depending how long the old man lived he could have telled his son a story or two) he may have ended up siding Daemon III in 236 AC some other such nonsense.

How often the royal houses intermarried prior to the Conquest is an interesting question. It must have happened from time to time to seal a peace treaty or something like that, and I certainly imagine to have been succession wars and the like where, akin to the Hundred Years War, a Gardener-Lannister branch supported by Highgarden tried to win the Rock, or a Gardener-Durrandon branch tried to install themselves as Storm Kings, etc.

In the North one could also imagine succession wars between various Stark branches who took over previous royal lines in the North and eventually fought for supremacy after the current main line had died out or was extinguished in a rebellion.