Complex sentence: In all four corners of Darbar Sahib the Holy Tank (Sarovar) was cleaned by Sikhs and in early 1980s a big hall was built replacing many Old Sikh period Buildings.
Split into simpler sentences: In all four corners of Darbar Sahib, the Holy Tank (Sarovar) was cleaned by Sikhs. In the early 1980s, a big hall was built to replace many Old Sikh period buildings.