Since the first solution helped many moroccan developers, i am going to update it to use some new ES6 features like Async and Arrows.

The first thing you need to do is create a simple map Google Maps JavaScript API :

<script type="text/javascript">
    init = () => {
        const mapOptions = {
            zoom: 5,
            center: new google.maps.LatLng(29.54619, -7.36133),
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        const map = new google.maps.Map(document.getElementById("map"), mapOptions);
    };
</script>
<script async defer
    src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=init">
</script>
<div id="map" style="width:650px; height:500px;"></div>

As you can see the map is splitted in two. To fix it we need to set administrative.country feature visibility to off, which will remove the borders and the countries, then you need to load custom Geodata from a FusionTablesLayer source and draw the borders again :

<script type="text/javascript">
    init = () => {
        const mapOptions = {
            zoom: 5,
            center: new google.maps.LatLng(29.54619, -7.36133),
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        const map = new google.maps.Map(document.getElementById("map"), mapOptions),
        mapStyles = [{featureType: "administrative.country", stylers: [{ visibility: "off" }]}],
        mapType = new google.maps.StyledMapType(mapStyles , {name: "Maroc"});
        map.mapTypes.set('maroc', mapType );
        map.setMapTypeId('maroc');
        layer = new google.maps.FusionTablesLayer({
                query: {
                    select: 'geometry',
                    from: '1S4aLkBE5u_WS0WMVSchhBgMLdAARuPEjyW4rs20',
                    where: "col1 contains 'MAR'"
                },
                styles: [{
                    polylineOptions: {
                        strokeColor: "#333333",
                        strokeWeight: 2
                    },
                }],
                suppressInfoWindows: true,
        });
        layer.setMap(map);
    };
</script>
<script async defer
    src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=init">
</script>

Note that you will need an API key to use the Google Maps JavaScript API, and finally the div that will hold the map :

<div id="map" style="width:650px; height:500px;"></div>

And the finale result will look like this

Morocco Map