I do agree PP-kei and James.
However, since you asked and I'm here, I just made the quickest overview. Note that it's my view and my understanding.
---------------ancient age----------------
100000-10000years ago Pre-historic era: Ancient people come from overseas, islands of Japan cut off from Asian continent .
↓
10000years ago-3rd century BC Jomon era. People lived on hunting and collecting.
↓
3 BC-3AD Yayoi era. Introduction of rice cropping. Numerous small village-states founded.
↓
3-7th century Kohun era. King of Yamato become dominant and expand. Introduction of Buddhism via China&Korea.
↓
6-8th century Asuka era. Yamato gov. and emperor as ruler established.
↓
8th century Nara era. Laws and ruling system strengthened.
↓
8-12nd century Heian era. Aristocracy. Peace. Rise of feudalism and samurai class.
↓
---------------middle age-----------
12-14th century Kamakura era. First shogun gov. founded while emperor remained as authority.
↓
14c Nanbokucho era. Emperor line split to two.
↓
14-16c Muromachi era . Two lines integrated to one. Feudal lords gain more power.
↓
15-16c Sengoku era. Feudal lords fight each other.
↓
17c Azuchimomoyama era. Nobunaga & Hideyoshi win the country. Introduction of western culture along with Christianity.
↓
17-19c Edo era. Ieyasu defeat Hideyoshi and establish Edo gov. Peace. Ban of Christianity. Restriction of foreign trade.
↓