Use Quick Selection Tool (W) and select mountains. Use Eraser Tool (E) on gradient layer to remove it from mountains. To deselect use Cmd/Ctrl + D or Select > Deselect.
Now I return to foreground rocks and decided to slightly change color tone. For this I used an adjustment layer "Color Balance". Go to Layer > New Adjustment layer > Color Balance... or click on icon on a Layer panel). Set values to each color and tone as shown in image below, set layer Opacity around 70% and create Clipping Mask from this layer (right click on layer > Create Clipping Mask or use Cmd/Ctrl + Opt/Alt + G). In this photomanipulation the stones with a blue shade will look more realistic and not distracting. Among other things, we have a night landscape.
Now that we have created a basis of the picture, you can start adding the main parts. So you do not mess up I'll start with the village. As with all previous images place image "Alps village" in working document, on top of all previous layers (I always open the folder with my resources, and for ease of operation drag the desired image in the working document). Do not worry about the little scary view of the village. I will correct it a little later. Use the Free Transform tool (Ctrl/Cmd+T or Edit > Free Transform) to resize the layer like shown in the image below.
I use Pen Tool (P) to create a flat path and then create selection from path (right click > Make Selection, Feather radius 0px). Add a layer mask to remove interfering houses. In this photo manipulation I use fragments of houses in the middle of everything else I removed, because the other houses portions are in a different scale.
Now make the village a little more. I chose a small fragment of houses, duplicate original layer (Cmd/Ctrl + J or Layer > Duplicate layer) and on the layer mask removed all unnecessary, except the required fragment. Use Move tool (V) to move fragment in desired location. To flip horizontally, go to Edit > Transform > Flip Horizontal.
The same piece I located in other place, as shown in the figure. Principle I think you misunderstood and can create your own version of the village. I added another piece to bridge the houses. Now I will correct color of houses. Do not think that the night could hide all the defects. It is much easier to create a light, when all objects in the same key. First you need group all layer with village (select layers and use Cmd/Ctrl + G or layer > Group Layers). Now add adjustment layer "Selective Color".
Now add adjustment layer "Selective Color". For Red colors set: Cyan: -91, Magenta: -87; for Cyan colors: Black: -100; for Blue colors: Black: -100; for Neutrals colors: Cyan: +5, Magenta: +1, Yellow: +13, Black: -32. This correction make village on normal colors without blue tint. Clip this layer (Cmd/Ctrl + Opt/Alt + G) to group and move on.
Once we have dealt with the landscape and the village, you can proceed to the vegetation. Place image "Forest landscape" in working document (File > Place (Place Embedded)). Flip Horizontal image (right click on Transform mode > Flip Horizontal) and resize it with Transform Tool (Ctrl/Cmd+T or Edit > Free Transform).
Use Quick Selection Tool (W) to select the left fragment of forests and remove everything else by adding a layer mask. Go to mask settings (double click on mask and you go to Properties tab) and click on "Mask Edge" button. In "Refine Mask" set check-box on "Smart Radius" and make Radius: 3.0px. Then set Shift Edge: -20%. Use brush in this window to remove the excess from the edges of the forest and click OK.