To the north of Beleriand, there is a green meadow called Adgaran. Whenever the first spring breeze blows from the Belegail Sea, the migratory birds of Heslum migrate inland to bring the seeds of the flowers to Adgaran. The grassland will become a sea of colorful flowers.

Unfortunately, only the southern half of Adegaran has such a beautiful view, because in the northern part of the steppe, there are three towering peaks, which are called Sangolo Rum. At the foot of the giant peak, within ten miles, the color of the grass is gray and crooked. Flowers never grow on the meadows there, and even migratory birds are afraid to pass by. There are many caves in the Giant Peak, which look dirty and terrifying, and the depths are bottomless. In the center of the three peaks facing south, there is a huge steel gate, rusted and old. It was the gate, but it was so big that it was hard to understand how tall and so big a giant needed to enter and exit through such a door. This gate, along with many other small caverns, is known as the Gates of Angban, which leads to the fortress of Angban, which is beneath Sangolo-Rotim. Morgoth, the great enemy, may be simmering his own plot in it all the time, eyeing the fertile lands of Bereriand's in the south and the elves he hates.

To the east of Adgarland is the north-south Eride Luin, the "Blue Mountains", where the dwarves live except for the elves. The Blue Mountains stretch all the way south and form the eastern border of Beleriand.

Adegaran's western border is the Shadow Mountains Ered Wesling, and on the other side of the mountain range are the lands of Heslum, Finngo, and Fingon.

To the south of Adgaran, from west to east, are the Western Ryan Valley, the Ehorrias Mountains, the Dosonian Highlands, and the Los Blue Plains. The West Ryan Valley is sandwiched between the Aehorias Mountains and the Shadow Mountains. The mountains of Ehorreas surround the hidden city of Gondolin. The Dosonian Highlands climb south from the Adegaran steppe, forming the precipitous mountain range of Eredgolos in the south. To the south of the plains of Lothlan there are two great mountains, the one in the east is called Ryliel and the one in the west is called Simrin. The two mountains join the northern border of East Bereriand, and Simlin does not fully border the Dosonian Highlands to the west, forming an Agron Pass in between. And there is also a more open opening between Rayleiel and Simrin.

These mountains that surround the plains of Adegarand form a line of defense, which the elves call the "Siege of Angban". The Noldor elves of each faction guard these natural barriers against the great enemy. Fingon built the fortress of Balad Ethel at the foot of the Shadow Mountains by the Springs of Ethelsirion, the heights of Dosonian were ruled by Fëanor's third brother Fenalfin's sons Angelo and Egnor, and Shimrin and Ryliel were guarded by Mezlos and Calanhill, among the sons of Fëanor. The most vulnerable parts of the siege are the West Ryan Valley, the Agron Pass, and the gap between Simrin and Rylil, where Finalfin's son Finrod founded the High Tarminas Tirith on the small island of Torcirian, which was guarded by Finrod's brother Orodris, Celegon and Kurjufin of the Fëanor's sons built a fortress at the Aglung Pass and patrolled strictly, and the gap between Simrin and Ryliel was guarded by Maglor, the second brother of Mezlos, so the gap was called Maglor's Gap.

Angban Enclosure (from west to east):

Ered Wesling (Finngoh and Finngon) – Gondorin (Turgon) – Dosunian (Angrod and Agnor) – Aglon Pass (Kellergon and Kurufin) – Shimrin (Mezlos) – Marglor's Gap (Marglor) – Ryliel (Kalanhill)