That is your argument. Do you think that because of Greece was civilized long before Norway was that you could find a higher IQ average in Greece than in Norway?
Not necessarily, because no one factor controls IQ. I just argue that genetics is one important factor, and also that culture and IQ are symbiotic. High IQ people will tend to create a good culture, and a good culture will tend to benefit the populace in terms of its intelligence. In any given nation there could be other factors which affect things. Also, people migrate and immigrants flood into established nations, so even if a nation is the center of a very old civilization, if it takes in large masses of immigrants from other lands, its IQ could be affected.
IQ doesn't necessarily conform to economic performance. A constraining economic system, such as communism, will hold a nation back no matter how high its inhabitants' IQs may be. Also, a nation that is too isolated from other lands may be held back because it doesn't pick up ideas that other nations are sharing to their advantage. But the thing to remember is that such nations rise with surprising speed if the impediments are removed. The natural high IQ of the populace is unleashed and the nation rises.
China & Japan are good examples of this. China was impoverished and starving under Mao. But after his death, more pragmatic Chinese leaders chose to permit capitalism and look at how quickly the nation has become an economic power. Thirty years ago the tallest building in Shanghai was around ten stories, even though the city was one of the largest on earth. People were crammed by the dozens into shanties and small flats. Google a skyline photo of Shanghai today. It rivals New York City with soaring skyscrapers, many among the world's tallest, as far as the eye can see. But we knew this was all possible, because Chinese who lived outside the Maoist tyranny excelled (Taiwan, Hong Kong, etc.).
Japan is an island nation and for centuries they refused contact with other nations due to their isolationist feudal ideology. As a result new ideas never reached there, and old ideas stagnated. They lagged behind other high IQ populations in development. But once Admiral Perry opened the ports, the nation rose like a Phoenix. They were able to conquer half of Asia and give us a run for our money in WWII. And even when we beat them, they didn't stay down. By the 1960s they were booming again.
Compare that the African nations. They showed no development until the Colonial powers arrived. Those powers built those nations up, but when they departed those places went right back down again. We've dumped a zillion dollars into those places and it hasn't done a bit of good. South Africa & Rhodesia were turned over to blacks as thriving first world nations, and look what's happened there.