Use your brain, man. You really think that a collection of children and old men/women are going to be able to feed themselves, or mine, or fish? No, they'll be dead weight to the hunters. More mouths to feed. Plus, how many of the Makarite hunters are women anyways? Likely less than two in ten. With all the healthy adults of breeding age gone, they'll be unable to maintain their population and it will shrink drastically. Such a lopsided gender ratio will cause massive turmoil in their society, and whatever means they choose to resolve it (polygamy, monogamy, etc) will doubly-hammer their population. They'll be done as a power for at least three generations.
And yes, I'm concerned about how things will look internationally. Welcome to the big leagues: we can't always get by on the crutch of being the biggest baddest warriors around. Rome and China both had robust diplomacy. At the very least we should appear to not be worse than the Makarites; that will make the task of integrating Brushcrest and its alliance much easier.