In about 1450 B.C. an Egyptian woman would have worn a robe tied in this manner. This garment would be incredibly easy to achieve for fancy dress costume purposes.
NOTE - No sash has been used to create this style of robe. The front is left to hang, rather than be pinned at the back. Then the back is drawn to the front enclosing the front sides when the back is tied in a knot under the bustline. This garment right is based on the rectangle pattern for the robe above and the pattern has been shown again.
When illustrated this way, it assumes you will stitch a shoulder seam or cut the piece on double fabric.