Map 19 connects to the western edge of Map 16 and to the southern edge of Map 18.
The space to the east of the eastern mountain range represents the Chasm of Doom.
In my mind I've always seen the Chasm eventually opening into the ocean between Pham and Tal, but I've never drawn the southernmost boundaries of Pham. Map 20 does show the northernmost boundaries of Tal.
Map 19 shows the capital of the Midland Empire, named in rather utilitarian fashion merely "Imperial Capitol."