The situation became more complicated with the landing in Murmansk of 130 British Royal Marine Light Infantry on 6 March to prevent the Germans  from gaining the White Sea coast and the Murmansk Railroad. By June 1918, an assortment of British Royal Marines, French artillerymen, part of a Serb battalion, Poles, Red Russians from the Murmansk Soviet, and some Red Finns occupied the railway line from Murmansk south as far as Kem. The arrival of British reinforcements and an Allied plan for them to link up with anti-Bolshevik units in Siberia prompted Trotsky, now at peace with the Germans, to send 3,000 Red troops northwards. In July these troops were disarmed and seen off by the British, who advanced as far south as Sorokka.  British-led forces defending the railway line included a battalion of 1,400 Red Finns and the Karelian regiment also known as the "Irish Karelians" after Colonel P.J. Woods of the Royal Irish Rifles who raised and led the regiment formed of the local Karelians. The situation of the Viena expedition began to deteriorate. The Karelian regiment stationed in Kem attacked the Finnish troops at Jyskyjärvi on 27 August. 18 men were lost. The next attack came against Luusalmi on 8 September when 42 Finns were killed.  Subsequent battles were fought at Kostamus and Vuokkiniemi in September-October. The Finnish troops withdrew to Finland on 2 October.  Of these troops, 195 survived and made their way home; 83 were killed. The British forces withdrew in October 1919 and the situation of the Russian White Army collapsed.
Question: How many different groups of people occupied the railway line from Murmansk south as far as Kem?
Answer: 6