The Eradication of the Everlasting Dragons

Ok, so I was going through the Duke's Archives on my dragonoid character and this got me thinking. 

Even though Seath is a mutation, the other dragons just like Seath show signs of being an intelligent race. When still being alive they lived in the Ash Lake under were Lordran now is therefore taking up no needed space from the lords. They were also clearly much weaker then the lords as it took only three of them to destroy the whole race and overall they show little agression towards other races.

The game never gives the reason for them being eradicated. It does though show that they are peaceful, they only attack if provoked, they were willing to share their knowledge with other species and that it was possible for the two species to crossbreed.

think the lords wiped out dragon not due to them being a threat but to show who is the strongest

I would also like 2 note it was not just the lords who solo the dragons
Gwyn had legions of knights and great archers (dragon slayer Ornstein has 72 dragon/drake  heads in silver knight set room)
the witch had her 7 kids who are  very power wizards
and nito never really fight them just made them all 2 sick to fight back
 
the dragon seem very smart in game but for all we know they may have been clan based and prideful to work as a race (unlikely seeing as they getting wiped out and no one that prideful)

a very interesting point about the dragon heads in the silver knight set room. I really never thought of that before

It does say in the beginning that everything was covered in gray crags and archtree's so I believe the dragons did inhabit the larger part of lordran.. and so in competition for living space they had to battle with the lords and their party

First off, the heads in Anor Londo are drake/wyvern heads, not dragon.
Which were likely killed by the silver Knights, or Gough/Ornstein themselves, for sport, or in defence of Anor Londo (item descriptions say that the silver knights were tasked of defending the princess, who just happens to be in Anor Londo)

Now, about the OP:
I haven't really thought of this before.
It didn't take only 3 lords to kill the dragons, don't forget Gwyn's army, who used thunder in the intro, Dragonslayer Ornstein, and Gough who also led an army of archers specialized in dragon hunting. The Witch of Izalith, and Nito played a support role, as they are not seen actively attacking the dragons, but rather spreading fire and disease over a large area, hoping to weaken them and restrict their movement. We do not know for sure what Seath did that could hurt the other dragons, but i'm guessing crystal/moonlight/soul magic.

Dragons are a highly intelligent race, one of them managed to survive, and collect hundreds of scales and turning people into dragons over time, one of them has developed sorcery, and written books, in a language orignially foreign to their kind, one has harnessed Dark Magic, with no apparent corruption, even though Dragons are not related in any way to the dark soul. It is no doubt that they are intelligent, maybe even more than the various humanoid creatures of lordran.

As for the reason, i don't know; and if i knew, i don't think i could explain it
I'm gonna go out on a leg and say that they didn't like to see their everlasting world being changed, and seeing new forms of life (the dragons themselves being treated like elements, part of the environment, rather than live creatures), coupled with Seath's growing obsession with immortality, probably made the dragons feel threatened by the undead and Seath, as the latter saw an opportunity to "collect samples" of the scales off the corpses of his kin, and in the process steal the crystal that artificially made him  immortal.

Seath might be one of the main causes of the war.








Of course this is pure speculation.

I posted something that relates on a topic just a minute ago, but I'll touch on it again, I don't think that the Dragons demise is solely related to random events leading up to the Lord Souls.

We know that the before the Flame the Dragons ruled over a land covered in crags and archtrees. Ash Lake seems to be a dimensional bleed-through. I believe that the Dragons created the Gods out of boredom, though naturally they are Gods to humans but nothing to the Dragons.

When the Dragons create the Gods they continue to live out their little lifecycles, going about business as usual in what would be a "God Antfarm"and the Gods create the undead (all speculative but we see that they do in fact exist with the Gods in the opening cinematic) but this is where things get tricky because it is all PURE SPECULATION: I believe that there is a greater Creator(one true God?) who brings the Flame into existence to change from the Age of Ancients into the Age of Fire. Otherwise there is no readily available cause for the Flame to just POP UP. Unless the DkS universe subscribes to Chaos Theory.

Buuuuuut that's just my $0.02.