[JeffF.]

I think small numbers are a hallmark of Tolkien's Middle Earth. in the Silmarillion the Army of Gondolin was said to have numbered 10000 at the Battle of Unnumbered Tears. When Turgon abandoned Hithlum to move to Gondolin he was said to have taken 1/3 of the Noldor with him and yet the larger number of his folk were of Sindarin origin. Let's say the 10000 was 2/3 of his army (leaving 1/3 to guard its seven gates and city walls. If 15000 represents his army and of those say 7000 were Noldor (& 8000 Sindar) then the Noldor overall were a small population.

Gimli's statement that only 1/3 of Durin's Folk were women and that not all of those married would also be representative of a population that is small and hard to recover numbers from disasters. Though numbers are not given for the Battle of Dagorlad the numbers of Dwarves that fought on either side was said to be few. A reasonable explanation for this was that in comparison with other kinds of folk they WERE few in number.

Tolkien does not describe some huge Haradrim cavalry charge at the Battle of Pelennor Fields. The Haradrim Chief and his horsemen are said to have seen Theoden and that few of Theoden's men were about him. Theoden "becomes aware" of him and though "fewer in number" their superior knighthood routs the Haradrim. This is not a Tolkienesc description of a huge charge rather a small engagement within a larger battle.

Though no canon exists for it I do believe that Erebor was the largest concentration of Dwarves. The realm of Durin's Folk, of the Eldest of the Dwarf Fathers, seemed to draw dwarves of all the houses. They shared Khazud Du with Broadbeams and Firebeards and their army in the War of Dwarves and Orcs had contingents from all seven houses.