To get your deeds for cities 3, 4, 5, and 6, (if your domain supports more than 4 cities) you need to attack wilds to collect Marks to craft into deeds.

1. Requirements for Each City
Level
City 3 Requirements:
10 Augustus' Marks, 5 Tiberius' Marks and 2
Caligula's Marks
City 4 Requirements:
20 Augustus' Marks, 15 Tiberius' Marks, 9
Caligula's Mark, 4 Claudius' Mark, and 2
Vespasian's Mark

2. City 5 Requirements:
20 Caligula's Mark, 15 Claudius' Mark, 9
Vespasian's Mark, 4 Titus' Mark, 2 Domitian's
Mark
City 6 Requirements:
20 Caligula's Mark, 15 Claudius' Mark, 9
Vespasian's Mark, 4 Titus' Mark, 2 Domitian's
Mark
(Notice the Marks for City 6 are the
same for City 5)