At level 23, the good places for you go (solo or group) are:

Qalia:
20 – 22 Skawlra Rock – Inner Groups / Quests
20 – 22 Upside defense garrison – Cyclops
21 – 26 Coterie Infineum Sanctuary (Lower)
22 – 25 Strand of Ancients (Turtles on the beach)
27 – 32 Coterie Infineum Sanctuary (Upper)
27 – 32 River Valley (Quests North and south of the river about mid-way through the map) (the place you show at this post screen shot)

Thestra:
21 – 25 Adyinn’s Watch & Surrounding Areas
23 – 28 The Ruins of Trengal Keep (Inside) (very good xp, very bad drop, if you need gear go other place)
25 – 40 Southwatch missives
25 – 26 Swamp south of Wardship of the Sleeping Moon – Quests and kill mobs (Slough griffon, basiliscin, and roughcast wolfs)
27 – 28 Swamp south of Wardship of the Sleeping Moon – Quests and kill mobs (peat mosquito, creeping quagmire, wetfoot fairys)
29 – 30 Swamp south of Wardship of the Sleeping Moon – Quests and kill mobs (cypress dryad, limnodian frog, and swamp krokodus)

KOJAN:
forget Kojan after level 20.

There are long quest lines for get nice gear at your level too.

* Qalia:
1- Hunter League quest line, start at Neamsong Bunker, but be adviced that you will need full group for complete some steps;
2 – Cotterie Infineum Sanctuary (CIS) quest line, need full group, mobs are 4 dots and KOS, but have very nice gear.

*Thestra
1- United Races of Thestra (URT) – look at 3 rivers and renton keep, there are quest givers who give you quests for Rare gear.

*Kojan
1- there is a tomb of a king there, but I forgot the name, get a group, good gear.

At 25 you can start the shadowhound or the unicorn quest line. You will need kill a lot of things and make a lot of quests, so that questlines bring you to level 30.