I've always felt that the Fall of Constantinople in 1453 was the beginning of the Dark ages of Eastern Europe...
And possibly the crowning of of Charlemagne on Christmas day by Pope Leo III as Holy Roman Emperor was the beginning of the West emerging from their "middle" ages.
Also, consider the final expulsion of the Muslims in 1492 from Spain/Portugaul by the Spanish in their Reconquista of the Iberian Peninsula and also the following expulsion of both Muslims and Jєωs who would not convert to the True Faith within the Christian empires. I would think this, perhaps more than any other date broght an end to the middle ages and the rise of truly Catholic kingdoms and a golden age.